I haven't found the skills to be unbalanced, with a few notable exceptions. Medicine is just terrible, since it's primary use can be done untrained with no check by using a Healers Kit. Performance didn't seem to fit, considering how many different tools duplicate the same effect, but XGtE helped solve that issue by encouraging doubling up. Some skills are situational, like Animal Handling, Slight of Hand, and the various Intelligence skills, but they have their usefulness. The only one I find unbalanced is Perception, and the easiest fix to that is to change several uses of it to be intelligence/investigation instead. Social skills are going to be needed by the social characters, but they're balanced among themselves. Stealth is a useful skill, but already balanced by the desire for Perception. Survival is almost necessary while traveling off-road, but you really only need one character with it.