I've been both to an FBO, DCA, ATP and that's where I'm instructing. DCA is a place I wouldn't recommend. Granted, they have hands down the best training, but the cost is just way too much and they say they have connections in the airlines, but you never see them. ATP actually has printed letters of lowered minimums to the regionals if you go through their program. However you won't learn much. When I finished my instructor ratings at ATP, all the examiners would tell the managers at ATP that they could tell that I didn't do my training at ATP. Kinda harsh. But they will get you done in a very timely manner and they have the connections into the airlines. If you ask DCA they will say yes, but if you ask to see a document they can't produce it. I loved my training at DCA, but they are really gonna put you in debt. My advice is to do training at either ATP or an FBO. As long as you get a good instructor, you'll be fine.