1. Oklahoma. Maybe in 1943, it was good in its time; however, the first time I saw it live was in the early 70s revival at the Palace, and I thought it was agony to get through. In my pantheon of awfulness, the top is reserved permanently for everything to do with the Ado Annie, Ali Hakim, Will Parker subplot.
2. Fun Home. I know a lot of people on this board love it. I think it is a bloody bore, although I do admit to liking a decent amount of the CD.
3. The Threepenny Opera. I am willing to concede that I may not have seen a decent production yet -- I sat through Alan Cumming and Sting productions -- but also the highly acclaimed version with Raul Julia. Hated all three.
4. Not sure about Cats. I don't know if it got the kind of reviews that would make it eligible as 'overrated'. If it did, it is eligible to be tied for #1 with Oklahoma.
5. Meta-musical: Fosse. Not a true musical IMO, but still totally awful (again IMO), despite getting a lot of great reviews and winning the Tony.
6. Others that may not be good enough to be eligible for 'most overrated', but still bloody bores IMO compared to the reviews and awards: Once, 2 Gentlemen From Verona, 25th Annual Putnam County Spelling Bee, City of Angels, Into the Woods.
7. Good, but just not as good as the hype: A Chorus Line, Annie. Book of Mormon.