Thanks Annaminna and Ifria. I think that proves that for me at least, I made the right decision when I bought TS2 rather than TS3. (It's just possible that TS3 base game might run on my computer; and in November 2012, I was definitely a latecomer to TS2.) FranH has a point about it being good for us that EA/Maxis stopped developing TS2 -- we don't have to worry about our mods stopping working because EA brings out a new EP. But from their own point of view I think they made a mistake in bringing out new Sims games incompatible with TS2 rather than building on what they'd already done. Their developers really excelled themselves when they brought out TS2 (despite its well known bugs), and, when you've done something as good as that, why start again from square 1?

Having said that I don't want any new EPs, I would be prepared to pay EA for a patch that fixed all the major causes of corruption. That would make a great game into a near-perfect one.

I'll have to repeat Peni's answer and say everything. I love all the age groups, how I can mold the game play to what I want, the small details such as sims opening a draw when they cook, the lighting, the way sims react to each other, the genetics, how I can just about run any business. For me Sims2 is just about perfect.

I think it's easier to list what I do not like.
I don't like that EA left buttons that corrupt hoods
I don't like how the neighbourhood renders from lot view
I don't like not being able to own hotels
Then there are other minor things I wished they had included such as cuddling on a sofa with a toddler, having a cat sit on someones lap and climb up trees, placing empty bottles onto a bench instead of on the floor.

I told my mom the other day that it's like a doll house. I like that it's really a toy, not a game. There's not just one way to play. Starcraft, Diablo, Pharaoh, 1602 A.D.--those are some of my favorite computer games. Sims 2 is just qualitatively different.

The genetics system.

Let me put it this way: If TS2 had Create-a-Style like TS3, it would be a LOT better. As it is I like TS2's memory system better and the animation is more smooth, at least on my computer.

I agree it's more of a toy than a game. As far as games go I like Angry Birds.

I love everything except that I wished cats would hop on your keyboard, hop on your lap or snuggles against your feet when you are sitting down.

I wish they would have made kids and toddlers fall asleep on a dog, or allow dogs to sit next to their master or follow their masters around the house. Little details like that would have been awesome.

Yes dogs are far to independent in sims 2, they should at least come up and get excited when your sim arrives home from work. Kids run and cuddle the parent, the dogs could have run around like crazy and tried to jump up or lick a hand.

I like pets better in TS2 than TS3. They look better for one thing. Though I do like horses in TS3.

The horses were the only reason why my daughter wanted my Sims 3 game. So that's what she plays now, Sims 3 base game+Pets.

On general level, the fact that everything sticks together as it should - no big loose ends like in TS3 and TS4. The open world was certainly a great idea but they never thought it through; the same goes for emotions (or, to be exact, more complex emotions) in TS4 - and no Twallan or Pescado around this time. TS2 had a solid base at the beginning and was well thought through till the end of the series.

On personal level, the fact that it is a great tool for the players' imagination. I know that at least half of my (and probably everybody's) game is played out in the mind, not on the screen. This can get tedious as well, however, so it's great that the game is capable to shake you up just about anytime. E.g., it nice when two Sims that you have groomed carefully for each other since their childhood fall in love, but it's even better when one of them falls heels over head (sorry, but I find the medieval turn of the phrase much more logical than the modern one) for a townie whom you haven't even really noticed, leaving you with a big problem of the only kind you should have in a Sims game.

My absolute favourite thing about TS2 is it's continuity from TS1. It's not perfect but in my opinion it's much more believable than the timeline in The Sims 3 (Kaylynn Langerak being older than Mortimer Goth and all...). I was always a big fan of TS1 and from the first time I tried out TS2 I just knew it was the way a new installment in a series should be - better than the last. The developers added so many crucial things to The Sims 2, like being able to create and decorate your own neighborhoods, better graphics, choosing a hairstyle and eye colour instead of just a head, the genetics system, sims being able to get pregnant and give birth... I could go on for hours!
In my opinion that's exactly how TS3 and TS4 should have been - clearly more advanced than the last game, in all ways possible. And while I can say, without a doubt, that I enjoy those two games, I still don't really consider them to be better than TS2, they are simply different. Obviously there's been development and added functions but with TS3 I felt like the developers mainly recycled stuff from TS2 (most social interactions and animations from what I have seen, for example) and while that's not necessarily a bad thing.. Well, I just wasn't feeling it, so to speak. I don't think there was the kind of significant change I would have wanted and hoped for.

The storyline and its continuity is something I also appreciate. They brought back some of TS1 families and added those 25 years - we see Mortimer as an elderly gentleman, Cassandra as an adult woman, Bob and Betty's daughter as a struggling single mom.. I think it's pretty moving how much attention the developers put into these things back then. While I like many things about TS3, I just can't stand what they did with the premades who I love so much.

Okay, this post has gotten long enough Sorry for getting a bit soppy there!

Wait, who was Bob and Betty's daughter? I don't remember anyone with the name Newbie.

Brandi Broke. Her surname is her married name.

I think it's Brandi, she married Skip Broke so that's why her name isn't Newbie.

Ninja'd.

Sorry, Peni .... I couldn't write "everything". I confess that I would have loved a semi-open hood, which would be a variation of Sims 3, and what I hoped was in Sims 4. And I'm no fan of the borkage, such as the all-too-easy ways for newbies to corrupt their hoods and their game.

Many things, though ... and more things than the other three series.

Most of all, I feel that Sims 2 gives you the most independence of the four series, including where you place and how you design lots (though Sims 3 also has building cheats) and how you play out the stories in your mind. I get a better sense of my Sims world being MY world. MY dollhouse. And this game appeals to all ages. I think EA has overlooked that now. Pity.

And no angry poops or dying of embarrassment. Thankfully.

It's also great for people who just wants to build and be an architect. So many endless possibilities

The sims 2-sims' facial animations are separate from the body animations. I think. It could also be some kind of lag.
Anyways they can exchange a family kiss while sour faced.
And hug someone while at the same time looking very suspicious!
I have pics.

^ That's actually both a positive and negative thing, depending on how you see it. Yes, you can combine poses and face expressions, but you can't make new face expressions. I wish there was some way to make new face animations...

Anyway, I like the posing system much better in TS2 than in TS3. Maybe because I'm more used to it, and because you can combine poses.

One of the things that particularly appeals to me is the way a neighbourhood evolves (in a non-Darwinian sense!) over time. No great cataclysmic change, but a birth here, a death there, someone moves out to live with someone else, teens grow up and set up a home of their own, teenage sweethearts pair up in adult life... All little changes, but over time they add up, and 50 or so sim-days down the line it's a very different neighbourhood.

And I like the way people, houses, even particular rooms or objects acquire a history of their own. Yesterday I was playing a house with a potted palm tree by the front door. That was a gift to the current owner's grandfather, when he was sort-of platonically dating a recently bereaved widow. That would have been about Day 55, and it's still there 90 days later. And if little Catherine, when she grows up, moves out to live with someone else, I'll try to remember to pack that palm tree in her inventory when she goes.

And as others have noted, there's the genetics. I've got some seriously ugly sims - ugly, but characterful - and I love to see how much of their facial quirks gets transmitted to the next generation. I've got a whole subset of sims sporting what I think of as the Nibblet Chin. Tristan Nibblet had a wonderful chin, he could have dug up roads with it, and it's still manifest to some degree in all of his grandchildren.

And yet, you know exactly how it got that way. That's my favorite thing about TS2 - that I can witness every single moment that happens in every single sim's life. I know them all, from birth, to death, and to the next generation carrying on with their own lives.

A lot. But to mention a few, because I prefer TS2's art-style to TS3's, wide range of 'life stages' (I know TS3 has controllable ghosts and imaginary friends, but they're not comparable to my werewolf-servo and evil-plantsim-witches), the ability to control every single corner of your neighbourhoods, and the best thing of all, of course the infinite customisability of TS2.

(and the most important thing is that it's so light it won't blow up my old little laptop to pieces)

I love (almost) everything. Mostly the way they look - so cartoony and cute - and the small details [such as sims opening drawers when cooking]. Building is a breeze [when I try to build on TS3, it lags.] I love how I get more control over the neighbourhood and can design it to what I want it to be - although, for the most part I play American suburban neighbourhoods.
Although, I wish there are more baby/toddler poses like in Sims 3.

That its over 10 years old and it still keeps me amused, entertained, pleased and impressed

I like the Sims more. In the Sims 3, sure, you can customize them with even more sliders, but it's so much that you end up making them wrongly portioned and going back to a template but all of the templates are ugly. And the Create-a-Style not only gives us less creators (recolorers) but you end up making EVERYTHING one color.