I've yet to see Ave Q, but I also love Phantom of the Opera and Sweeney Todd.
Avenue Q is just really funny. I like Sweeney Todd, but I have a problem with Phantom independent of the quality of the musical itself really. When I first went to college, it was the height of the craze for the musical--Good Lord, do you realize as of last October they've done that thing over 10,000 times? Anyway, way back when I was a big Fat Boys fan, I spent my first year or two of college in film school learning all that obsolete and expensive equipment no one uses anymore and I lived in a dorm full of theater and dance majors. And they would chain-smoke Marlboro lights and drink diet cokes and snort cocaine and stay up all night every night dancing in the hallways and singing Phantom of the Opera music. Over and over. Punctuated only on rare occasions by Depeche Mode. I shit you not.
That one part where Sarah Brightman screams on the soundtrack STILL gives me the uncontrollable urge to whip open a door and strangle somebody.