The rooms at Pop are 260 square feet, the rooms at WL are at least 340 square feet. The beds are queen size at WL and doubles at Pop. I would never stay there again if there were more than two of us in a room, it may be true that you will only sleep in the room (it isn't for us, but it may be for some people) but if you DON'T SLEEP, that's a problem. My husband and I aren't overweight, but he is over six foot and sharing a bed there sucked.
There are about 730 rooms in WL, while there are almost 3000 in Pop. That is A LOT of people all sharing the same food court, same buses, etc. If you don't care for food court food, that's your only choice on property.
The boat ride to the MK is lots of fun and quick, if it's cool or storming the bus ride is quick and efficient. We never had any trouble with the bus system at all.
We enjoyed the dining option at WL, the fabulous pool and relaxing in the beautiful lodge.
Did I give you enough reasons? lol