Originally Posted by flyastrojets
And to actually answer your post.... and these are my opinions and mine alone.... By order of preference of best F seats
738
757
M80
The 75's have the old leather chairs, but they are wider than the M80's, so that wins for me.... not that I'm all that wide, but still...

And there is IFE. No such animal (or screen) on an MD80 unless you bring your own.
As for United, their 757's do have video and most have the "empower" power ports. Their 737's have audio, but no video that I've seen.
I agree with Astrojet's ranking. Maybe it is the shape of the seats, but I believe there is more legroom on the 757 than on the MD80. I also like the big brown seats. I think they are more comfortable. I have to adjust the headrest on the MD80 to get comfortable.
There is something about the 737 I prefer over the other two planes. It may be subjective but I just like the 737.