The good news is that ANY of the four choices is likely to get you there in about 30 minutes; an hour is perfectly safe for an ADR.
Your best bet for consistency is the resort monorail (MK-Contemporary-TTC-Polynesian). Yes it is slower than the express monorail (MK-TTC) but most people go for the express monorail, and you may have to wait for the second or third train.
The resort launch (MK-GF-Poly) is small and I would not rely on it when Wishes is over because it will fill quickly. If you see it at the dock or nearly there, by all means hop on it. But waiting for it, especially in a long line, is not your best choice. Waiting for the launch to come back a second time is the worst scenario of the four.
The (large) ferry (MK-TTC) is OK if there is not a huge herd of people already in line. It holds several hundred, but you will not want to wait for the second run if you can avoid it.
The ferry or the express monorail will take you to the TTC. It is a short 5-minute walk to the Polynesian from there, and even in the dark you can't get lost! (Turn right/west, and follow the road.) So don't be afraid of the options that take you there.
Notes: The Wishes show lasts about 15 minutes (the sound track is 12:31.) Depending on where you watch, it may take you 10 minutes to walk to the exit.