I took mine back in 2003. The ACA certification is what most guiding company advertise their guides as having from what I still see, so I think it is still probably the best one to get. I learned a lot about how to teach the sport and got a lot of information about how to improve my own paddling. We did a good mix of class time, pool time, river time and review time. Did video analysis of our own paddling and how to recognize and offer sound advice for others.
The ACA is good about having a solid outline for the course that the instructors use, so I think that the information covered will be about the same in every course. I would put a lot of thought into who you take it from. The teacher(s) really make the class, and a lot of places do hire out of their own classes. I would look for a fairly seasoned instructor and a reputable shop.
Guiding was a lot of fun, I loved to introduce people to the sport, only wish it was year round here and made you a millionaire
You know where you want to work out of?