Speaking as a current raid leader that already has cleared all of the content, i still have fun raiding on this server simple because the raids are quality and challenging. That being said, not everyone agrees that more challenging is better and it creates difficulties maintaining a deep roster of alternative characters and backups, which is extremely helpful in even normal TBC raiding. In conclusion, creating a fresh roster and progressing from kara to swp seems like a near-impossible feat at this stage of the server, but horde is probably your best bet for NA as there are still players but not many good guilds anymore. My guild is almost the only NA on alliance and we actually have new recruits faction change to ally all of the time.
Don't get me wrong, i'm not discouraging you to play here or even start a guild. Hell, I hope i'm wrong and it's ezpz. However, if you are ever compelled to ask for advice or further explanation, you can hit me up on discord Prugaros#7030