Schedule and price should determine. I avoid WN connections, which is fairly easy for me as my principal airport is BNA. The trouble with WN connections is that if your connecting time has been shortened due to late aircraft arrival, your seating options are no longer optimal- if they've boarded Groups A and B already when you get to the connecting gate.

I'm not a huge fan of Delta for many reasons, from too-crowded SkyClubs, to rude or under-informed phone agents (after a four hour wait for a call back), to mishandled refunds. I could go on and on. I won't. Delta- meh.

Unless you have top tier elite status with an airline, I say go by price and schedule.