Delta does not allow raw-fed animals or animals that live in a home with raw-fed animals, even if it's only occasionally. So I'd venture to guess most of the members of this forum excluded on that basis. Even if you just give a bite of raw meat or a RMB once every couple months, you can't participate.
TDI...I can't do TDI because they don't allow service dogs to also be therapy dogs, which is annoying, stupid, and discriminatory. So I wouldn't use them just on the principle of the matter. They are the most common one around here, though. Their test has changed recently, but it used to be super easy. Logan passed the test 2 weeks after I got him, but we didn't register since it would have been a waste of money since he would be unable to participate shortly after.
I've been meaning to look into TDInc and Love on a Leash, but I simply haven't had time yet. But I have heard good things about both organizations. The biggest problem would probably be finding an evaluator in your area.