[Tetsuro P12]

Hi,
 
I'm looking for the next pair of headphones and I'm looking for suggestions on the type.
 
What are the strenghts of those two types? In particural if I choose the supra-aural I would go with this one: http://www.head-fi.org/products/beyerdynamic-dtx-501-p. It's a mini type and I haven't been very pleased with a similar headphone so far (this one: http://www.head-fi.org/products/akg-k-430-foldable-mini-headphone-silver). I have been a bit happier with some IEMs but they suffocate me a bit. So are they really just better in general? Same price range (70$/€).
 
Thank you.
 
P.S.: Soundstage is very important to me since I listen to rock music.

 

[GREQ]

On-ear 
Pros -  better separation or more cohesive sound due to larger drivers. often better FR response overall (better timbre more natural)
Cons - bigger (less portable), uncomfortable pressure on the ears after a while, 
 
In-ear
Pros - superior isolation, extreme portability, usually excellent sub-slamming-bass
Cons - some cheaper models are somewhat fragile, usually coloured mid-range (less natural sound)
 
Neither of these will provide you with an impressive or expansive soundstage (compared to large, full size headphones)