I'd go for a 17" iMac, I think it's a great machine, I'm using an older version of it at school. I really like the heigth/angle adjustment possibilities of the screen.
The 15" iMac should be good too, but 1024x768 is too little for my XCode and Terminal windows too feel really comfortable.
I don't have much experience with eMacs, they offer much bang for the buck I guess, but I'm an LCD man...
BTW, what do you mean with auto upgrade to Panther? If you wait a few weeks, it should be bundled with the computer.