I have an imperial alt on Grand Master Zym and the Imperial 'pvpers' in the lower bracket are the worst collection of keyboard turnning s keying illiterate morons I have ever unfortunately encountered. If you want to roll Imps I'd recommend that awful low population server.
If you want balanced pvp with quality people on both factions then I recommend Mind Trick, it has a great community. Slightly more imperials but an increasing Republic population feels like it will eventually level out 1:1. I have toons on both factions and have found that both the 50 and 10-49bracket has resulted in competitive enjoyable games. vs the Zym server where most of the imperials don't understand how the speeders to the other turrets in Civil War work...