"The Happy Time" has a wonderful score; the OCR is lovely. I've never seen it on stage, however, though there is a Tony Award performance of the title song and "A Certain Girl" which is worth seeing.
"The Act" I recall liking only two numbers: "City Lights" and "Arthur in the Afternoon", the latter perhaps more for the staging of the number which helped it quite a lot.
I saw "Steel Pier", and it really had book problems. I enjoyed the score and performances though, as well as what was a rather monumental choreography job by Susan Stroman (huge dance marathon numbers), but, with its producers unable to apparently get the "They Shoot Horses, Don't They" rights, the book didn't really work. Wonderful OCR though.
I'm not going to rank the others, as nearly all of them have given me much pleasure over the years. I've probably listened most to "Cabaret" and "Chicago". Otherwise, I'll just say that "70, Girls, 70" is worth checking out for being one of the shortest runs of a Broadway show with one of the most delightful scores.