Well, I'm torn. I actually like WL better than Poly. But I can't deny that Poly has ALL the other resorts beat, hands down, for transportation. It certainly is convenient for getting to and from MK and EPCOT, especially if you have strollers and don't have to fold them down when you ride the monorail.
However, WL is a REALLY nice resort, IMHO. There is a nice boat that goes to MK from there, and it is stroller/wheelchair friendly, unlike the boat from Poly. True, the WL boat is shared with FW, but it is a very nice ride to MK. It can be a bit crowded coming back from MK at night, but so does the monorail, to be honest.
I don't think you can do wrong with either, but if transportation speed and convenience trumps atmosphere (can you tell I really love WL?), then Poly gets the edge. We actually chose Poly this time around for this very reason, since we have a 6 YO and a 2 YO, who still needs a stroller a lot. Being able to stroll a conked out 2 YO DD all the way from EPCOT to Poly without having to disturb her is worth the extra cost for us, this time around.
But please don't take my post as a dis to the Poly. It really is a great resort with a great atmosphere and wonderful dining. It's just that WL has sort of become our favorite. Poly's a VERY close 2nd, though.