What is the reason for taking the class? If you're thinking of working in the outdoor industry, you'll need to re-cert in a few years, and NOLS/WMI has classes all over the country. If it's just to learn, that isn't as important. Also, is the course going to be at all activity specific? Taking WFR courses hosted by my rafting company and doing scenarios with our regular gear felt more useful than getting a bunch of ski patrol & avalanche scenarios when I didn't work on the mountain.
Ultimately, it comes down to the individual instructor. I've never had a bad WFA or WFR instructor (a smattering of both WMI & WMA courses), but I've had some that are more & less memorable, and remembering the lessons is pretty important. But, you won't know how you'll mesh with the instructor until the end of the class.