Like Jeebus said, Simbology and Simlogical have some great mods. However, if you're a picky jerk like me and want to tweak the game to within an inch of its life, you have a ton of options. The Director's Cut is packed with useful mods, and if you just want to grab and play and not have to concern yourself with possible conflicts, you'll have a much improved game experience with a selection of mods from that.
However, there are so many very annoying, nonsensical, or plain limited things in the game it's worth hunting down mods that improve anything that doesn't satisfy you. Very strictly, there are only a handful of fixes in the Director's Cut that are necessary to prevent game-breaking bugs the rest is flavor.
