I have the new iMac, I caved in and bought the Super Collection for it. I finally figured out where to put cc/mods on it, the Sims 2 folder was pretty well hidden. I'm just wary about downloading mods that may not work for the SC as it's missing the last two expansion packs (Freetime and Apartment Life) Any recommendations?

I think you may have answered your question yourself. Basically you can't use any mods that require Freetime or Apartment Life. In general, if a mod is available in different versions for different EPs you should get the EP6 Bon Voyage version. Downloading hacks from Pescado's MATY (More Awesome Than You) is especially easy: Go to this Hacks Directory and then drill to your highest EP (In your case Bon Voyage). Fortunately Pescado wrote many of the essential mods for fighting corruption. I'm a bit surprised none of the Mac users here have answered you yet, but I'll tag @lordtyger9, as he probably has something useful to add to my ideas. There are other Mac users among the regular posters here, but I can't remember who they are.

As a Mac user you have one big advantage over us Windows-bound players: you can actually buy a modern fully licensed and supported version of The Sims 2. I wish EA would do something for us Windows users, either themselves, or lease it to another, less hidebound, company who is interested.

And M&G ^ While M&G was technically sold as a stuff pack it works more like an EP as it upped the game engine from AL.
Look for mods/CC/lots that are for BV or lower configurations. Mac also has a file limit as well so be careful on what you add.

As others have said, basically look for mods that are compatible with Bon Voyage, or aren't EP specific. Pescado's BV mods are fine, most of TwoJeffs are (though if you want to use ACR, you'll need to use ACR 1 rather than ACR 2), criquette's fixes (Better Nightlife, terrain replacement, etc) are fine as they were created for the Mac, and a lot of Chris Hatch's standalone stuff is BV-compatible - though the expansion-pack type stuff isn't as it requires all EPs.

Lazy Duchess's stuff is mostly designed to work on the Windows executables though, so although a few things may work the majority won't. Can't say for certain which, as I'm currently on a Sims 2 holiday due to work getting in the way of setting up my game again on a new iMac, so I've not tried any of them as yet.

You'll also need to watch out for CC objects, as some stuff will just not work, no matter if it was cloned from a base game object or not. Sometimes it's just that the wrong flags are set - I've been able to drag a few files into Windows and edit them in SimPE - but others are beyond what I've been able to figure out. Lighting related stuff can be a bit iffy in particular. I'd advise putting any downloads into a testing folder until you've checked in game that they (a) show up at all, (b) don't crash the game when you browse to their bit of the catalogue, and (c) actually work as they're supposed to if they're anything more than deco.

The worst issue with the current 64-bit version of the Sims 2 Super Collection is that Aspyr seem to have accidentally broken "boolProp dontMergeNHFlora false" when doing the conversion from the 32-bit game. It's been reported many times, but alas there's still no fix. So while you can do all the other steps to make the hood visible at great distances, you won't be able to make your trees show up as they'll just flash blue or go invisible if you try it. But on the plus side, the game doesn't require you to do a lot of hair-tearing to get it to run at the resolution of a modern monitor, and it does run pretty smoothly. I miss some of the content from the missing EPs and SPs, but mainly get by without missing the functionality too much. (Though I've added in the 4-Key locking system from Simlogical to give me the ability to have pseudo-apartments.)

Sorry that I have not been very active recently. I do play The Sims 2 regularly on my old iMac and in my case I am still playing with the 32bit version.

Anyway I have found that pretty much any mod that came out before Free Time is fine, I would test a new mod to be sure if it is unclear, but if it says that it is compatiable with BV or Seasons and does not say that it is for FT or AL it is going to work on a Mac in my experience.

Most all of Pescado's Mods work as do most of Squinge's and most of BoilingOil's and most of Inge Jones' and most of Cyjon's work fine. All of these creators are good about listing their mod's needed EPs, if in doubt you can test them. I have also found that creators of mods here on MTS are good about stating whether their mod is compatiable or not, just look to at the guide to what EPs are needed, I have found that it is pretty accurate.

Agree - basically anything works as long as it isn’t made for an EP that came out after BV. This is fine for older content, but it can make for a hassle when trying to download from newer creators or from sites without posting guidelines because a lot of folks don’t list the EP compatibility of their mods. (Or they clone an object that should be BG compatible but use a mesh from FT/AL… that sort of thing.)

Keep a folder within your Downloads for "newly added" mods in case you ever add something that crashes because it’s incompatible and you should be fine!