If you have M&G, that's considered your latest EP. It's a "mini-EP" since the latest release and was piggy-backing off of AL's game engine or core functions, which had several changes from the earlier games. If you don't have M&G, then AL is your latest.
You'll want to use the latest EP/M&G as your base for changes in the game unless otherwise noted. You may also want to use the Bodyshop that comes with M&G (if that's your latest). Not sure if there are any changes between the AL and M&G version other than possibly some added items (which most likely would be read by the wrong version), but at least you don't end up with mods that don't work if you install them in the wrong place as per potentially confusing instructions.
---
The UC doesn't use Pets to run, but it uses the title card from the "Fun with Pets" compilation pack, which is a completely different thing - that original compilation had Pets, Family Fun and M&G - M&G is kinda the clue there, not Pets.
There's been several compilation packs that have 3-4 packs in them, and the UC has most of them in the setup (no idea why) - Double Deluxe was released quite early on (in a few variations), then University Life, Fun With Pets and Best of Business as three separate compilations in one go, some time after AL and M&G were released as separate packs.
https://sims.fandom.com/wiki/Compilations_of_The_Sims_2Regardless of compilations and the UC, original release order of the separate packs (separate EPs and M&G in particular) is still what decides which is your newest EP/SP.