For a cross bike, I'd vote for steel. You sorta need an aluminum bike to fully appreciate steel in the end though, so I guess you can't go wrong.

Either way you are going to have a fun bike!
In the normal world, steel frames are cheaper than aluminum. If the Surly costs more, and we are just talking frames here, there must be some premium for the name, or the Kona is a killer bargain,, or "steel is real" is for real.
One thing to consider with cross bikes (unless you only intend to race) is to be sure it has bosses for fenders or racks. These bikes look like they both do but many cross bikes are so race oriented that they will leave them off. For commuter bikes, they come in handy though.
I have a steel Gunnar Crosshairs and I ride it to work every day. On the weekends I ride it for fun - I'm working up to the on/off road double century this summer. My back couldn't take that on aluminum!