Boards
y-fronts
I got myself a few pairs of these the other day, and it's like a whole new me:
http://marksimpson.com/blog/wp-content/uploads/Smooth%20Y%20gang.jpg
Briefs were too baggy and boxers were just FAR TOO INTRUSIVE in terms of bunching up in your jeans and RUINING EVERYTHING.
M+S "mens slips". £3 for 5 pairs. Do it.