I have played both sides, and I find it incredibly funny when the opinion of Republic general chat is that Sith is more popular because of Horde and all the kiddies want to be dark. And when I am playing on the Empire side, the general opinion of their general chat is that Republic is more popular because of the movies and all the kiddies want to be hero light jedi.
This leads me to believe that the only thing I can say for sure is that both sides are equally retarded. The other side is full of kiddies because of this or that. This side is where all the mature adults play. Us vs them.
It's as if people can't have logical or justifiable reasons to play on the opposing faction.
As for PvP, it's primarily luck based. You may get people who know what they're doing. You may be facing a group of L50s that know what they're doing. Unless you are in a good group with a good amount of expertise gear, it's up in the air if you get an advantageous match-up or not. Some people may have a good win ratio as a level 10. Others may have an awful ratio all their leveling career. It isn't 100% luck, but whether you are doing well or poorly isn't 100% skill either.
The generalizations need to stop!
Oh, and as for me? I prefer the Empire side because of their stories and their voice-acting.
I don't mind female Jedi Sage and male Trooper/Varic from Dragon Age 2, but they aren't amazing either. I was fully wanting to love female Trooper/female Shepherd from ME2, but she did a poor job. It sounds as if she has a stick up her butt.
The voice for the Imperial Agent/female Hawke from Dragon Age 2 is amazing. I believe the IA has the best voice of all the characters. Female Sith Warrior and female Bounty Hunter aren't bad either.