I use model paints (GW, Reaper, Vallejo, Army, and I still have some Poly S) as well as craft paint. I only use craft paint on large scale projects (ie building, terrain, battle boards) for the reasons already mentioned.
To second Jimmy Zimms, I have converted all of my model paints to dropper bottles that I picked up dirt cheap on eBay.
I also add an agitator to every bottle. Back in the day when I was an ignorant youth I used BBs and the corroded in the bottle. Now I buy Hematite beads at the craft store. They are relatively cheap, wont corrode/rust, and are heavy enough to actually agitate!