I was originally going to go for the Epic, but after thinking about it thoroughly I realized two(ish) deciding factors of my going with the Evo
1. I don't need a keyboard- I played around with typing on the Epic and it just didnt feel right to me. After using a Hero for a year, it seemed unnecessary and the Evo's on-screen KB is just so smooth.
2. Better support community/hardware/software (IMO)- Again, after being spoiled with the Hero's great support community, I found it natural to stick with HTC to root/ROM to my hearts content. I like the bigger screen, the kickstand and Sense UI. The Evo is one of the reasons why I decided not to get a netbook, I can do whatever I need to do on my desktop such as course work, and everything else on my Evo
Hope that helped...