Love the 6. I just helped my mom purchase a loaded up 6s with V6, auto, leather, etc - great car. My only gripe would be the auto tranny which can be a bit "confused" at times. This was pretty appearant at Mazda Rev-It-Up when driving them on the short auto-x track.
If my CSVT had less miles on it, I would be making the tough decision between the manual-tranny 6 and the Mazdaspeed Protoge.
The TSX looks like a darn near clone to the 6. I just can't justify the extra 5 grand (nice incentives out there now on the 6) and higher interest financing (6 was zero% for 60). The TSX has got a pretty darn strong 4cyl tho.