I'm mostly using some texture changes/NPC makeovers and a couple of new player houses. Aside from that, I'm currently using the "slower degradation" mod, which helps a lot. I like the idea of equipment degradation, but in vanilla FO3 it's ridiculously fast. It seems pretty ridiculous to me to have to carry 3 weapons just to be able to have a single well-functioning gun by the end of a non-fast travel trip. The thing I like about this mod is that it has several different files, all with different rates of degradation - so you can just pick whichever one you want.
I also like "Nova interaction revised" where there is a momentary fade to black once you hire her. It's not something that sees much use (I've actually only used it once just to see if it works), but it's just nice to have some kind of acknowledgement by the game that something happened.