I've had very good luck with UPS. I've shipped literally hundreds of frames with them and only two have been "lost" for a while and none have been damaged. Maybe it's just dumb luck but I don't think they are any better or worse than the other shippers. I do think insuring the frames/bikes for a bunch of dough helps. I guarantee a box that's insured for $2000 gets at least a second look over one that's only insured for $100. Insurance is cheap.
Curt Goodrich
Minneapolis, MN