As far as a parts/frame deal goes, it would be alright if I was sponsored by a company that would let me design the frame, or give me a decent enough mass produced frame to ride. I mean, I could happily pick a frame from the Zoo or Echo ranges, but there are some companies I just wouldn't ride for. I remember when there was the Base Team try-outs, and the winners were taking apart their bikes with decent frames like Leesons, a Pace 250T(?) and I think Austin was riding a Levelboss, and building up a bike with poor geometry just so they could say they were sponsored. Which seems a bit pointless to me.
Because I have a good enough job that I can pretty much buy what bits I want, I don't feel I'd want a sponsorship deal, unless it included any of the following:
1) A fat 4x4
2) A decent clothing deal
3) A Koxx XTP