"I was between Brussels, Ghent, and Bruge."
I'll just complicate things further, and add Antwerp to the mix.
The question of which of these four cities is the best base, not to mention which is the best, is perennially debated. You won't know how you feel about that until you've seen all four. All I can do is give my personal reactions (below), and advise you to read as much as you can about each one, to see if one seems more appealing to you on your short visit.
Personally, I loved Antwerp, liked Bruges a lot (yes it's very touristy, but you can find quiet corners too), was slow to warm to Ghent but liked it enough by the end of my day there, and found Brussels a snooze except for my wonderful Art Nouveau tour with ARAU: http://www.arau.org/en
Logistically, Ghent is between Bruges and Brussels, and it's only about an hour from Bruges to Brussels, so you can visit all three from a base in any of them. And getting to Antwerp doesn't take much longer. Trains on all these lines run 1-2 times an hour and are unreserved, with no discount for advance purchase. In other words, wherever you end up staying, you can go to any of the others on the spur of the moment, even for just part of a day, easily and cheaply. So don't worry so much about choosing the "right" one.
I'll just add that if you want to see "beautiful sites" and you're staying in Brussels, be sure to limit your sightseeing to the very center. The Grand Place is indeed grand, but most other parts of the city range between "meh" and "feh" in appearance. That's why the Art Nouveau tour was so valuable - the gems are scattered, and the nondescript (and sometimes, downright ugly) is everywhere in Brussels. For eye candy, definitely choose one of the others..