I have stainless, glass and plastic fermenters. i use the stainless most of the time, then when it's full I use my plastic buckets. Only when I'm making a slow fermenting beverage like cider or mead will I use the glass carboy, and then only if I can fill it and drain it without ever having to move it. Right now I have one cider in a carboy and 5 gallons of cider vinegar, but they'll be sitting until they're ready late this year and won't have to be moved.
As far as the quality of the results I don't notice any real difference between the three materials. It's the skill and techniques of the brewer that determines the quality of the beer, not the fermenter material.