CHB is my favorite. Eminence is crap. ProMar 400 is also good, though I get more of a dead flat look and less roller marks with CHB. I use Wooster SuperFabs for flats. Sherwin Williams doesn't sell Wooster so I guess if I had to buy roller covers there, I would go with the Purdy White Dove. I use 3/4" nap, but sometimes that is too much for a DIY'er. It's thick but flat paint should be put on thick and then spread out evenly. If 3/4" is too much, then 1/2" would be fine.

IMO, SW does not make ANY good ceiling paint.

Is there a different one you'd recommend? Need all the advice I can get! ;)