If I could keep the essential mods to keep the game safe and then am told to pick only ONE other mod:

Community lot skilling.

It has changed the way I play (I always loved this feature in Uni, because time flies if your students go to community lots often). In the rest of the hood, though- the hood really changed from a number of families to an actual community feeling.

It means that my musical sims can play the piano at the restaurant or be the band at the nightclub; that my logical sims can play chess in the park, that my fitness sims can do yoga anywhere - and gain skills. It also means that my knowledge sims can teach skills to other sims in the library.

It also means that my poor sims in that tiny starter do not have to put any skilling item into their already cramped place.

Because sims get hungry on community lots, there are often coffee and Exnem's dessert cart - I am not giving up that cart either

I think the single most important "I cannot play without it" mod for non-corruption-or-RSI issues for me is nowhatsthis.

If we include Repetitive Stress Injuries, then Macrotastics. I tend to think of that as a necessity, though, more in lines with nounlinkondelete.

Oooh yes community lot skilling is essential! I forgot that wasn't vanilla. I use it for uni a lot too.

Excluding bug fixes and anti-corruption mods, I'd have to say that my must-have mods are Smart Beds (stop sleeping in your daughter's bed!) or Community Time.

I mean, my must-have is always going to be SimBlender. Can't live without that mod. Or Inteen. But that's just because of my playstyle lol

Turns out I don't have as many mods as I thought I had (I've got like 20 in total and even then I don;t need all of them really), so my cc is actually just stuff I want for additional building and house decorating themes that I personally dont think I can do as well with only the content that comes with the game. There are some mods that I would be sad to not have like some of MATY's and Cyjon's fixes though most are because I'd just freak out over why certain sims are the way they are and others are because my computer would probably die without them. Nothing major though because I do like the game as it is

The first one I thought of while reading this is "cancelable make bed interaction". It's so annoying, it always made me want to activate testing cheats and force reset the Sims to make them stop.

Besides that one and the usual anti corruption mods, I don't have many.

- That one you mentioned of keeping surnames after being married. The way the game does isn't how it works where I live, so yeah.

- Numenor's mod to place the open/close sings everywhere. It may not look necessary but I have a lot of businesses and being able to place it on walls only is very limiting...

- LdDarcy's pie menu fix. I guess it's not the case in English, but in Spanish the pie menus are a chaos. Like the wardrobe having the change into outerwear and swimsuit options in 2 separate sub menus. Just, why?

- More columns for CAS and the other menus. Idk, I just need them...

- No supernatural wants/fears. I wanted to keep the game as vanilla as possible. If Maxis wants non-Knowledge Sims to dislike supernatural things, I guess it makes sense. Well, I tried to resist using this for so long, but I couldn't. I really couldn't. All the friends of my warlock kept rolling the want for him to be cured. Every. Single. Day. One would think they would eventually accept it and let him live his dream of being a warlock. But nope.
And let's ignore the stupidity of rolling both the want and the fear to be cured at the same time.

I think that's all, I could live without all my other mods. Most of them are small bug fixes anyway.

I still remember once way back in the past I had some sims cheat on spouses in NPC mode while on community lots because I added more expansion packs and never knew this could happen unitl later on and now that I know it's been a fear that led to my adding ACR to my game to put a stop to that mess.I just have to tune ACR correctly to fix that issue so it can't happen again unless I want it to with some households.

I have a few hundreds of gameplay mods that I consider to be essential that come from creators like Boiling Oil, TwoJeffs, Pescado, Chris Hatch, Cyjon, Squinge, etc...

To name a few that weren't already mentioned in the thread (at least I don't think):

Clean UI (Greatcheesecakepersona)
Triplets & Quads (TwoJeffs)
Do Homework (Monique)
Job Options Mod Set (Lamare)
Child Support (Monique)
Abort Bed Making (Pescado)
Phonebook (Phaenoh)