For Design, Zelda: Wind Waker is probably my favourite. Visual, sound and storytelling designs all worked together to make something greater than the sum of the parts.

As for gameplay, I like systems where the controls are fairly simple, but they're all you need for a game (none of this "press A to do FUCKIGNEVERYTHING" nonsense). Tight systems like Smash Bros and Portal appeal to that.
I also like puzzle elements in other games, even though I don't particularly like pure puzzle games. I think Portal wins on that one again, although I've heard very good things about Bioshock for that too.