My buddy has the Epix from at&t and his battery last all day. He runs the internet, talks, texts, and other stuff and his battery meter hardlly goes down in a 8hour day of work that I am with him. Mines loses 1 bar from just getting on the internet for 10mins. I have the extended battery also. Why is that.

depends on many factors.

assuming everthing else is equal- if he has better coverage on ATT than you do on VZ then his phone has to use less power to transmit to the cell tower and his battery will last longer.

I know one flavor is better at battery life than the other- so could be GSM is better than cdma.

could also be that there is better firmewar on the epix. We're still waiting on the first firmware update from VZ and seems we should already be on the second one had they not kept rejecting them

couple thoughts..

The backlight has a massive impact on battery life (as does WiFi), try turning it down if you can.

The epix has a bigger battery stock (1450 mah vs 1100 mah i think)

The battery gets better over time and with use. The battery life i'm getting now (6 months in) is far better than what i originally got.