Cable & Deadpool vol 1-8 (All 50 issues)
Deadpool Classics Vol 1 - 3 (The run by Joe Kelly is one of the best. Vol 4 is due early next year)
Deadpool: Suicide Kings
Deadpool Max is a bit different, but with just 1 issue- it's tough to say but so far, it's pretty good.
Uncanny X-Force just started and it depicts Deadpool perfectly.