Main stats for combat rogue...is mastery?

Hello guys and girls,
i was thinking to start playing a combat rogue in PvE and every1 who I asked said that mastery is better than haste. As we all know haste gives rogues energy regen which is really important. Is there a particular reason to stack mastery and not haste? I would appreciate some help XD

Combat rouge must pick haste over mastery in raiding. Haste is the way to go for pve, mastery only for pvp

Haste makes your hit faster as well as for energy regen
Mastery make your killing spree hit harder because of proc main gauge