Mr. Driller For me, this is the best iPhone game ever. It's quick and fun, playable by any kids I happen across, and just all in all simple and fun.
Sigma In my opinion, the best Match 3 game ever. Vector graphics and 3d scrolling on either side makes for a left brain/right brain combo hit of fun and puzzling that can eat up tons of your frustrations/hours.
Farm Frenzy A great and well designed app, it's fun and difficult to get through all the levels.
Space Miner Humor + Resource Mining + Role Playing Genius add up to one of the best games ever. The only drawback is that I wish I could buy increasingly additional sectors & ship upgrades after I'd completed the regular game (more than once).
Osmos Beautifully rendered and with such nice textures, this game is a feast for the eyes, and gameplay is awesome, multifaceted and challenging.
Vector TD A close second on the TD games list for me- a must have port of the classic Candystand.com flash game- albeit a little bit harder on some levels than the Flash version.
Tiny Tower Very much like a Tamagotchi in it's addictive sense, this game has cute little 8 bit bitizens, and the small little attentions you must slather onto this game make it lots of fun.
Plants vs. Zombies "We're coming..." Awesome gameplay, endless depth, levels and challenges. Humor galore and the most polite zombies ever add up to a classic all-time game.
Infinity Blade Retina screen + Unreal Engine= Awesomeness. There is a subtle depth to this game (with the update) that isn't obvious until you've played it for a while. It's a game that requires practice and swiping finesse to master.