I have chars in both sides, and both sides are good and have good players.
But there are several differences in normal warzones..
Imp side:
- more leavers, they give up too early;
- few healers;
- very little and in some games inexistent communication in chat;
- many good pvp players without guild, many solo queues and less premades in normal warzones;
- more nervous and rude players than rep side...well, they have Sith
Rep side:
- group more;
- less players without guild, more pvp guilds;
- more healers;
- good communication in chat;
Well, this is my summarized view from both sides as a pvp player.
edit: for those who says Imp side sucks, i won 100% of the games against Reps pugs without healers ^^
Give more healers to Imp side, they can balance the ratio.