Aug 11th 2010 7:35PM I think this is just a matter of taste. I have both an 80 rogue and mage and I enjoy the mana system more. Keep in mind that mine is a pvp perspective.
Energy resource management just feels like "work". I constantly have to keep track of my energy to make sure that I can react. For example, kicking a healer during a cast. Like a poster above mentioned, it feels like running out of mana every 6 seconds, but for a very short time.
With mana, I cast what I want, when I want, and start thinking about mana regeneration when I hit a certain treshold or if I feel like the fight may require some conservation.
Two different mechanics, each has its pros and cons, personally, I'll take mana over energy any day.