I'm very fond of Leaders. I love my 721. Although there are criticisms about their geometry being off, its still an amazing frame nonetheless.
I haven't heard much about Aventon, but it seems just okay- if you want it go for it i guess. Ive also been eyeing the 17teeth Evo, although i know nothing about it. You could look on craigslist for some better frames used probably as well. You can probably snag a fuji 09 track pro, or a EAI bareknuckle(steel, but great frame). Precursa's, etc, and the list goes on