I don't know what people are talking about in regard to the fit. The band running across the ear-pieces is taut so the pressure holds them to to your ear, same as any others. The AKGs are maybe smaller and rounder but IMO, this is much more comfortable; they still go over you whole ear.
OK, side-by-side comparison.
Frequency response;
BD: 5-35000 Hz
AKG: 18-26000 Hz
Frequency is (VERY) basically the pitch of the sound; higher frequency will produce a higher pitch, more more high-end in the sound, vice-versa for bass response. It seems like the BDs are way ahead but actually, your ear can only hear frequencies between 20Hz and 20000Hz (if you're lucky; I can only get 22-16000Hz. Too much rock), so both of these will cover the entire spectrum of human hearing.
Impedance:
BD; 250 Ohms
AKG: 55 Ohms
This gets a bit tricky here and depends on utility. Basically, the lower impedance will be louder overall but that isn't necessarily a good thing. If your amplifier (i.e., MoBo or sound card) has a high impedance, lower impedance headphones may cause some distortion at higher volumes, as well as some frequency loss. TBH, I doubt this will really affect you; the impedance of either the MoBo or the sound card should be fine for 55 Ohms (which isn't really low impedance, anyway). On the flip-side, I doubt very much that the BDs will be too quiet. There's a possibility that the AKGs may perform better if you opt for onboard sound but it's a pretty small factor IMO.
SPL;
BD: 96dB/mW
AKG: 94 dB/mW
Basically, how loud they are. You won't notice 2dB difference. One thing that bugged me is that while AKG specified the rating as 94dB/mW, BD had it just listed as 96dB. This bugs me because decibels are not to a scale; they are a relative measurement and need to be compared to another pressure level to be meaningful in any way, so simply stating that it's '96dB' is meaningless. They do clarify it if you mouse over but still, that's annoying.
The connector on the AKG is a removable mini-XLR connection. It locks into place and you could have it as a permanent fixture but IMO, it's great because a) You can transport the headphones ad cables separately rather than having to wrap the cable untidily, which will help it last longer and b) if it breaks, you can just get another mini-XLR to mini-jack cable rather than having to strip the wire and re-solder the connections (can be a bit of a pain in the arse but not THAT bad).
Again, I'd like to stress that I have not heard the BDs and they might be incredible but I have heard the AKGs and they're the best I've ever heard. IMO, either will be a good purchase and I doubt very much that you'll regret getting either.