They are both amazing, The screen is great on the evo, and I have such an easy time texting, and also, even after the $10 evo data charge, Sprints plan is a better deal than Verizon, however, the incredible is amazing as well, and even though the screen is a bit smaller than evo, it is still crisp and colors are a bit brighter than evo. Either phone will serve you well in my opinion, and I have had none of the problems of others with these phones.
Also take into account which carrier (VZ or Sprint) has better coverage in your area.