Here's my list!
Eyeshadows: I'm gonna be frank and say that MAC's eyeshadows are really hit-and-miss for me, and there will be some duds, but the good ones are GORGEOUS. They have a wide selection of colours and finishes so you'll find one you like! In general I don't really like the Lustres because of their lack of pigmentation, but most of the other finishes are great
Fluidlines: I love MAC's Fluidlines. I believe my entire gel liner collection is MAC and Bobbi Brown, and 1 Stila and 1 Etude House. LOL. Thats how great I think they are.
Brushes: There are cheaper dupes out there, but I do belive MAC's brushes are worth the money. I've never had any issues with mine other than slight initial shedding. My favourite MAC brush is the 187.
Blushes: In particular, esp if you are a newbie to MAC, do try out Blushbaby - it's one of their most universally flattering colours.
Other things I haven't personally tried but get lots of love are Blot Powder (good for oily skin), and MSF Natural. Some people also like the MSF highlighters, and there are girls here who "collect" these things as they are also really pretty to look at, although personally I found I didn't like them as much. Still, I'm just listing them here so you can check them out for yourself