Like everyone else has said, a mountain bike is not ideal if most of what you want to do is road riding. If you want a bike which is competent on road and off, a cross bike is probably the best compromise.
Having said that, anyone who describes an entry-level Cannondale as 'an overpriced BSO' is an idiot.Yes, the build kit on it isn't the best (but what do you expect at that price), but the frame is about the best in the business, and if you replace the components as they wear out with upmarket equivalents you will end up with a very nice bike indeed (although still one which is not well adapted to road riding).