The boat to the MK is very nice from the WL, but we didn't find the buses any better from here than from the moderates. After many trips to WDW, it is our opinion that the transportation from any given resort is not significantly different from any other. The exceptions are going to the MK from the CR or going to Epcot from an Epcot resort. Generally, there is little difference in the buses. Yes, sometimes you are lucky and sometimes not so much. BUT overall buses come about every 20 minutes and the difference between the longest and shortest bus ride is only a few minutes.
FWIW, we only use transportation from the MK or Epcot resorts to sway any resort decisions.
WL is nicer than a moderate, IMO, but with a four vs five day trip, I would pick POR RR. It is an awesome resort, the RR are conveniently located, and it is only one destination that is a boat rather than a bus. AND, of course, there is a full extra day to be had.. It is a tough choice, though.
Whichever you choose, have an awesome vacation!