Sunland for CPL. Brian Westin has forgotten more about GA commercial ops than most of us have learnt... Used to work with him and learned a lot..he's a hard but fair task master and you would enjoy flying with him.
FTA ... strong focus on foreign contracts ... 'nuff said.
RQAC ... no first hand experience of them (but maybe a bit like FTA?)
Gil Layt's ... more laid back and perhaps more personal attention ... not a sausage factory.
Just my two bobs worth.