Fail.
I would argue that they are comparable only in the most superficial ways... I fail to see anything beyond a (mediocre) supernatural serial drama in Charmed, with no greater scope or focus. Buffy, on the other hand, can be enjoyed on multiple levels. While it wasn't always successful, Buffy was far more ambitious and as a result, it gets the benefit of the doubt with respect to its few missteps (of which I don't include Dawn, for the record).