I have both of this cans, They are both great bang for the buck headphones IMO.
Pro 80- If you want a close can with that is dark with good detail and bass go comes with a coiled cable and pleather pads (which I recommend to swap with HM5 pads and do a rope spacer mod). I prefer using it with rock and metal
Hi2050- if you prefer an open can that is brighter and more airy but not lacking in the bass department comes with a straight cable and velor pads. I prefer using it with classical and jazz
either way you can't go wrong. they are both excellent value for your money.
Cheers!