A Pro/Con list might've helped beforehand!!!

Fuck it, 70 quid down the drain..
carry on.
-=-=-

Note, everything below is entirely iDev based!

GLBasic

Can
Work..
This is a big selling point. If you're trying to decide, and Monkey won't let you see what it could achieve, you're going to decide based on the fact that GLBasic will damn well LET you! Even in the Demo.
If you're new, if you haven't attempted it, GLBasic does the job.
But don't expect miracles.

Can't
Shove a huge mountain of big sprites on the screen.
Backgrounds are limited, foreground sprites require work to get colours going, and dear god, don't get me started on the whole "No Pitch" thing.
That is one REALLY bad downside.
No pitch = entirely monotone sound effects, or 100 copies of everything, at different pitches!
Given that I'm so used to using PlaySFX(n,randompitch,randomvolume), that was Really Really bad!!!

...
But it does work, and it is at least half-decent.

If I hadn't already used Cocos2D to do SpikeDislike, then I might've stuck with it, but every time I tried to do something, I had a little thing in my head going "I've already done this before, and the last time I did this, it worked.."

If new : Use GLBasic
If already done it : Avoid GLBasic.

How
LoadSprite This
DrawSprite This,Here
Done

Monkey

Can
I don't know, the demo doesn't let me.
This is the end of the Monkey section, because the demo doesn't let me, so I don't know.

Cocos2D

Can
Sprites : Enough!
Text : Normal labels are a little slow at updating, bitmap fonts aren't. Use bitmap fonts for anything that updates ingame, but count your sprites, and use labels whenever you can!
Sound : CAN PITCH THE FUCKING AUDIO

Cannot
.. Technically it CAN do UILabel overlay stuff (ie GameCenter swooshy tables and things), but fuck!!! I gave up trying!

How
Make Object
Load texture
Put texture into object
Move object into screen
Keep track of objects and textures.. gah!

UIView

Can
Save your battery! A lot!
Since you're using the bog standard "How the iOS draws it's browser/etc" mode, you're really saving the battery by a bucketload.
If you CAN use this, go for it..

Cannot
Lots of sprites..
You're going to see slowdown as soon as you reach about 50 sprites.
Since it's all made of UIViews, each one you add slows things a wee bit.
It's not much, and the GLES that Cocos uses also slows down, the more you add, but UIView mode is a bit more obvious, and you'll get a little less out of it.
BUT.. That battery!!
If you can, you'll save a lot..

Bitchy Bit
Use OpenAL for the audio, 'cos trying to get iOS to play audio's a pain in the ass!

How
Same as Cocos2D. Tracking everything!
Tracking is a pain...


IMO, It's Cocos2D or UIView. or rather, plain iOS vs GLES.

Sorry GLBasic. You're almost there, but you're also not..