Well, I've been in MCI for six months and in my experience if price is a main concern for you, which it sounds like it is, then you might quickly find that Delta seems to be the best choice in my experience. Trip after trip, Delta consistently is the lowest price, and it's not just that they're matching what the others are offering ... they are the lowest price by some amount many times I've found.

AA is probably second, but in those cases they seem to have prices that match Delta's sometimes, but other times they're noticably more expensive.

I don't think I've priced one trip yet where Delta wasn't the lowest priced option (plus/minus $10, rouding for airport taxes basically) except maybe some MCI-CHI trips I flew on Southwest.