I'd trained in Karate as a child, for a few years, then later on in my late teens, I spent several years doing ju-jitsu. I just felt that I was learning very robotic movements, some of which I felt were too complex to condition into my automatic reflexes. I'd heard about Wing Chun, and its simplicity, and decided upon checking it out.
My class, whereby admittedly I've not trained now in over 8 months, my work shifts have changed, and being a dad to a new born has kicked the crud out of my energy levels, I'm getting to the point where I can go back. For me, the simplicity, the aggression and directness of it, combined with a very hard edged approach to training (occassional bare knuckle, full speed training, contact made, get on with it approach). Combined within a 2 hour class, we'd do around 20 minutes of nasty aerobic, basic fitness building work. It's truly amazing how many sloooow, good form press-ups you can fit in, along with stomach crunches, running, and chain punches you can do in that short period of time, just to get you warmed up for the rest of the class. You can see why I've not had the energy/inclination to go. There's only so many sleepless nights you can have before you're totally drained.
I also felt much more at home with the CMA too. They have a bad press sometimes for a variety of reasons, but I found the informal training approach combined with obvious results too much to ignore. For me, having done other arts originating from a certain island off the coast of mainland China, I found the bowing constantly and silent atmosphere of the training hall to be offputting, so that was another reason why I changed over. I agree to an extent that WC is something that would generally be the kind of art/system to complement another. And for that reason, I'm hoping to start sun style tai chi very soon. Just my tuppence.