You know there's a special forum just for talking about cases & cooling, right?
The H55 is a more expensive cooler and performs a bit better. It is currently on sale and the Evo is not on sale, thus the pricing is close. H55 has $10 rebate putting it at $45 shipped, versus $43 shipped for the Evo. At this kind of pricing, IMO the H55 "wins" in performance for only $2 more. The Evo is occasionally on sale too, for around $30. For that price it "wins" bang-for-buck. It would also have such a "win" if the H55 was at regular price.
There are other considerations. Are you okay with liquid in your computer? Do you have clearance for the tall Evo? Do you have a place to mount the H55? Do you have any future plans to re-purpose the H55? (FWIW you can make a bracket which will allow you to use it to cool a graphics card.) Do you not do rebates? The H55 is even more attractive with the rebate, but marginally less without it. If your case has bad ventilation the H55 might work better.
What kind of overclock are you hoping for?