Edit: Here, Sheldon's already got a good article for you:
http://www.sheldonbrown.com/kops.html
I really like the Thomson posts. They're extremely well made and easy to get ahold of. You've also got better options for setback/colour/length/diameter than w/ a Jaguar. You may want to try to track down some high res images of the clamp on each post and see if you prefer one design over the other.
Just my $0.02 ... but hopefully it helped a bit.