see whenever you ask a question like this you are going to get a variety of answers, each person pushing for his or her favorite.
I honestly am in love with all three of these, but they are so so soooo different. We need to know more about what type of show you are looking for, what other shows you liked, who you're going with etc.
Hair is definitely the most energetic I would say, with Heights coming in at a close second. But Hair is really interactive, lots of 4th wall breaking, like one big hippie party, it definitely is a lot of fun. However, the lack of strong plot does bother some people, I personally have no problem with it. yes, it does have a story, but really it is more about the music, the experience, and the social commentary. (All of which I think are amazing)
If you want a show that is going to make you think a lot and leave a strong emotional impact (with some very catchy songs along the way) then go see Next to Normal. I saw it the other day and it was unbelievable, I left the theatre in tears.
In the Heights is one of my favorite shows, its is very modern, a whole lot of fun, and heart warming too.
If you still cant decide, one thing I usually do is see which I can get the best seats for and that determines which show I'll see.
<-- Gwen Stewart, SOLoist at the last show of RENT
Cages or wings?
Which do you prefer?
Ask the birds.
Fear or love, baby?
Don't say the answer
Actions speak louder than words.
(Tick, Tick... BOOM!)