I used to play back when MTG first came out. I believe the last expansion set I ever bought/played with was Mirage. From there, MTG just got too expensive and complicated. The rules constantly being changed, cards being banned. Far too much for this part-time player.
Come to think of it, I was a terrible player. The main reason I started collecting was because of the cool pictures. My friends thought I was crazy. But IMO, some of those artists rock, especially Mark Poole.
As for my favorite card, I'd have to say Vesuvian Dopelganger. Just because it was cool.