I've owned most of the Ti frames...the number one choice without hesitation is:
http://www.moots.com
I would take this over a Seven, Litespeed, or any other in a heartbeat. I should have never sold my VaMoots (still have my YBBeat though).
I love steel and Ti, but if you've got the budget, I'd go with a Moots. I don't like Al because it can't be easily repaired, and tends to be stiff and harsh (that depends on the builder though...I would never call a Vitus stiff). CF doesn't send me...the frames I've ridden have felt dead, and I think Ti/steel are tougher in the bike world (ie to percusive injury).
That being said, a nice Rivendell lugged steel frame is a work of art. But so is Moots:
http://bender.annenberg.edu/tar/psychlo/psychlo.html
