Here's some comparisons asked and answered by someone else in your shoes -
http://androidforums.com/android-lounge/239206-trying-pick-phone.html
Absolutely stress that Bnice is right - make sure you hold each one and trust your gut a little, too. It's a phone, you'll be carrying and using it, and nothing beats a hands-on experience to judge which is right for you.
This is top-line tech, there are tradeoffs despite specs, so either is an equivalently good choice - but all the tech in the world won't matter if you don't like it in your hand.
If you do that, play with the menus even a little bit, whether you know what the features are or not, and then if you still can't decide, then go with whatever advice pleases you.
I still prefer the Evo for its stronger case (weaker glass), better cpu (worse gpu), Froyo (flash content matters to me on websites), better gps, specifically because it doesn't have a physical keyboard and it has a kickstand.
That's me.
What you'll prefer is entirely your business, and it's all 4G Android goodness so you'll be making it your own (appearance, applications and so forth).
If one were clearly better than the other as a technical tour de force, fewer people would have this question - it's not you, they're both great.
Plenty of people have bought one and switched to the other and liked the other better.
Going for trilogy - put your mitts on them before deciding and don't ask for salesfloor advice unless you already know the rep is a low-pressure type.