WL is great, love the theme and the pool with the waterfall that empties into it. The boat to the MK is great, but no monorail is the reason I would pick the poly. The WL busses seemed slow to me...maybe it is better now.
Poly is cool....as for 70's looking...well, kind of but not really...that's what people who have never stayed there say. It is theme just like it should be....just like Hawaii, etc. Poly has the boat to MK, busses...and of course the monorail, that's hard to beat.
You also get the nice beach area and view at the Poly, which is way better than the view at WL (as far as seeing MK, fireworks, water parade, etc).
The poly also has all of the little boats you can rent...not sure if WL had that, I don't think it did.
The new poly pool looks better as well....the WL pool was fun and they do have a hot tub, something the poly seems to still lack after all these years.
Either one would be a great choice...I would only go WL again if it was an issue of money....otherwise poly is THE way to go, hands down.