I have played Wind Waker on the original gamecube but I didn't get far nor did I get through the game and found everything in the game. Then again, I have never beaten a zelda game before and I find them rather hard to progress in. However, I also want to preorder Sonic Lost World so I can get the bonuses that you get for preordering.
Little biased, but I'm going with the Wind Waker HD. Original was great and I'm looking forward to playing it again. Lost World doesn't really appeal to me too much honestly.
Wind Waker 100%.
I don't find Sonic as fun as I used to, so I'd need to see something that would make me really want Lost World, whereas WW is a definite sell to me right now.
I would grab Lost World if only because it's a fresh experience and Sonic games have been consistently worth playing since Colors. I'd wait until WW drops in price, because I'd be dishing out almost top dollar for a pretty game with insignificant tweaks that while improve the old game, don't justify a $50 price tag. WW HD is semi-worth grabbing, but I'd wait until its cheaper or I could buy it used.
This is supposing I ever become interested in the WiiU, which is very unlikely.
Wind waker has little replay value, but it is a personal favourite of mine. The pictograph mini-quest for figurines was one of my favourite parts of the game.
I'd say Wind Waker because it's one of my favorite Zelda games. However it is just a rerelease of an old title. Man I can't believe it's been a decade! I was 11 when it came out.
Sonic Lost Worlds looks amazing but it's also a Sonic game so Sega is really a hit or miss with Sonic.
...I'd say Wind Waker, for this very reason. Sonic games have gone down hill considerably since Adventure: Battle 2 though it seems they're starting to get a grasp of it again what with the likes of Sonic 4, Colors, and this game does look fun...(but as Chromie said, it's Sega, could be hit or miss XD)
As was mentioned before, I'd say go for Sonic Lost World, and get Windwaker later on. Until you get Windwaker HD you can play the Gamecube version and decide whether or not you want the remake.
It's generally kind of hard to get a preorder gift after the game has come out, so keep that in mind, too.