I always felt that the NX-01 was the ugliest Enterprise. Not because it looks like an upside-down/smushed Akira, but because it does not comfortably fit the design lineage of other Federation ships.
It does not look like it would slide into the era of the Daedalus class followed by the Constitution class over the next hundred years.
I read on Doug Drexler's blog (before he shut it down) that when he was brought on board, they ship was already overdue and all he had time for was cleaning up the design that had already been worked on. He stated that (had he been there from the beginning) he would have just re-designed the Daedalus class slightly so that it looked good and detailed for TV.