Alright so we know when it comes to handheld graphics, Vita is pretty much king. But Iphones and Ipod touches have incredible graphics chips capable of beautiful visuals.
As I own an ipod touch 3G and Iphone 4 I am looking at the best looking games on them and comparing them to that of my 3DS.

The best on the I devices are

Infinity Blade


I shall compare this game to Kid Icarus.


Straight off the bat you can tell that Infinity Blade looks better. To be fair there aren't any screens of Kid Icarus that do it justice and in fact, Kid Icarus performs better than Infinity Blade. Infinity Blade runs fine on Iphone 4 but on 3G you'll encounter slowdown from time to time. Kid Icarus runs smoothly without any noticable lag at all.
Kid Icarus' gameplay is also a lot less linear than IB which plays like a minigame. Kid Icarus has inferior character models, certainly, but at points in the game you'll be fighting enemies 20 times your size and have loads of enemies flooding the screen at once in large well detailed areas.
So Infinity Blade looks better immediately, but in the long term Kid Icarus truly juices the system a lot more and performs more like a console game. Also the special effects are beautiful.

When it comes to shooters, the best looking one on i-devices (that isn't stripped down to bare bones like RAGE) is no doubt shadowgun. The game looks beautiful with its HD graphics. I shall compare it to one of the best looking handheld games ever... Resident Evil Revelations on 3DS.

The character models look more "realistic" than those on RE:R which have a more distinctive style

That being said, the texture and effects quality of Revelations blows Shadowgun out the water in this area.
In terms of the environments it is harder to compare

Resident Evil Revelations looks stunning but I think overall the quality of some parts of the environment in Shadowgun looks better. But Revelations also has much more interesting/varied environments with more clutter and such.

It's hard to decide a winner in terms of environment but overall Revelations wins.
Aw dont worry Shadowgun, you beat Resident Evil 4 iphone at least!
(but then again even resident evil mercenaries wins against that )

Infinity Blade looks amazing on the iPhone.

^
Epic Citadel impressed me more because it didn't feel so stripped down (ironic considering it is just a graphics showcase).

Why are you comparing a phone to a gaming device? The iphone doesnt have the best gpu of the phones, and the 3DS isnt the most powerful handheld gaming device either...

Currently on the market the Vita is more powerful. And the most powerful phones are HTC One X and Samsung Galaxy SIII.

3DS: 400x240

Iphone: 640×960

You cant really compare them in anywhy when it comes to graphics. Its like comparing Xbox/PS2 to Full HD.

Lykos, Why so many comparison threads? Just go play your 3DS if you love it so much.

^ True words. ^

Lykos, I never said you didn't play your 3DS. You just make too many comparison threads, you've basically run out of things to compare it with the PSVita and now you're comparing it to the Iphone.

If you don't like my threads, don't go on them.

I never said I didn't like them. It comes off like if you're trying to justify your purchase of your 3DS, you compared it to the PSVita in about everything and now you're comparing to the iPhone.