Go on, you know you want to!
Your top five musicals are the latest Normblog poll. Contact him via his site: there is a link there.
My first thoughts are these but I'm going to refine before emailing saintly Norm:
Singin' in the Rain: just perfect. Top of any list, whatever is permitted.
Les Miserables (aka The Glums): cheesy, but I do love it.
Wizard of Oz: still cannot accurately sing the words, but a standby from my childhood.
I also thought of these which I may want in a top five but wasn't sure if they would count:
Porgy and Bess: is it too operatic?
Sondheim's Sweeney Todd: likewise? (I saw it a few years ago and it knocked my socks off - an amazing piece of musical theatre)
Buffy - Once More With Feeling: TV episode length musical? Can that count?
I'll think this over more 'cos I'm thinking of new possibilities every time I type!