After all these years, the only Amiga game that I fiarly regularly play (and in fact I have the Amiga version on my PDA) is Dungeon Master. There's something fiendishly addictive about the game. It's not nostalgia either, I think that it's a very playable game, full of strategy and tension.
Life decision? I sold my C64 and entire collection of games for the half-meg upgrade to play DM in 1989. Looking back though, I wish I hadn't!