Rayman Adventures plays like a more traditional platformer when you connect a controller.
Morphite is a great ATV game and controller support is excellent.
Stranger’s Wrath is great, too.
Gear Club is a very good racer with a pretty greedy IAP system.
Riptide GP Renegade is another good racer (on hydro bikes) with fantastic water effects.
Haven’t tried it yet, but Inside should be excellent on ATV.
That’s off the top of my head. If you have been buying games on an iPhone, I’d recommend taking a look at your purchase history on the ATV — you may be surprised at what you find. Also, check out the “Playable with Controllers” list.