I've only been over there like four times, so take this with a grain of salt.
LM is most busy. It is much less busy just before the park closes. FPs are sometimes available by the Winnie the Pooh FPs. More than once, I saw people standing in a 60+ minute line when they could have gone over and picked up a FP with an arrival time that was 30-40 minutes away, lol.
On the day we were doing all three, the next busiest was the Belle thing, then the Ariel M&G. I didn't go into the Ariel M&G, but the Belle thing is worth a look-see.
If you want to try the LeFou Brew, consider whether you want to go get in line for something else, lol. We were all jazzed to try it and then realized we'd have to wait until it was gone to line up for the LM. Luckily, we did not care for it and tossed it out.
We got our LeFou Brew before we went to the LM and ended up having to wait to get in line until we were sure we didn't like it and threw it out.
I don't know if any of that will be any help at all, but good luck and have fun!