Agree with Dragon on the 767 200 vs 300. The 300 was by far a better flying airplane.
As for me, it's a tough call between the 767-300 and the 757. Both GREAT airplanes.
The 737-800, on the other hand, is a piece of junk (although I would give my arm to be back in one right now!). The cockpit is too small, the engines take too long to spool up, the overhead panel is circa 1965, the autopilot pitch control is AWFUL, the VNAV function of the FMS is worthless, and the gear is too stiff. Other than that, it's fine!
The 737-200 was a pu$$ycat. So easy to land, handled beautifully. Only problem was the FMS sucked (I know, I know, I'm kidding) and it was too underpowered.
I'm glad I got a chance to be an f/e on the 727, and it was my first jet, so I'll always have a soft spot for it, but it was getting pretty long in the tooth!
Despite what everyone else thinks, I thought that the md-80 was pretty nice. I enjoyed flying it, but maybe it was because it was the first jet I got an f/o bid on. Granted, it was slow, and the autothrottles were pretty rough, but I thought it landed pretty good, the fms was fine, the systems weren't too complicated, and the handling, while not exactly stable, was fun.
All in all, I would say that the 757 was my favorite, followed VERY closely by the 767-300.
I hope that I haven't bored anyone with that little rant. I meant to just vote for the 757, but figured I would talk about some others. It's been a while since my furlough, I must be going through withdrawl!
P.S.
So people are not confused, I flew some of the above at TWA.