I primarily fly Delta out of DTW, as I am a credit card member and I get 1 free checked bag per trip. I've had some issues with them, but generally customer service is good - if you're ever in a pinch, you can tweet @DeltaAssist and they reply super fast, too - and planes aren't too delayed. I've only had one flight ever been canceled, EWR to DTW, and that was because of weather, or so they said.
Planes are usually pretty clean and the Delta terminal at DTW is really nice too - they renovated it a bit back. Love the monorail.
My last flight was to Atlanta, back in October 2014 (side note: Atlanta is also a DTW hub and it's a HUGE airport. I've been there 3 times now, since a friend lives there, but always forget it's so big!), and I had no issues. I usually fly 3-4 times per year - last year was Anaheim, Nashville, and Atlanta, for flights, and this year is going to be Fort Lauderdale and L.A., if not more - and I've used Delta for all of those flights. I do want to try out Southwest at some point, since Delta can be pricey, but it all depends how badly you want to search for bargains ... I just booked my FTL flight for April for $186 because they were running a sale.