I preferred Zurich as a city, but Geneva as a region. I initially went to Switzerland for the skiing, and preferred the ski areas closer to Geneva, but ultimately spent more time touring europe.

Are you anticipating responses about French vs German cultural stereotypes in the 2 cities? My coworkers in a merged bank of french and german banks would tell you the regions are quite different culturally, particularly in workplace. I would concur, perhaps because coworkers were quick to point out differences.

I would advise you to consider where you have a fluency advantage.

You might also research you flight/rail options if you are hoping to use either city as a departure point for travels across EU.