First I'd like to thank Odacervicix for a well made post. His list really does include most of the best players on JC regardless of which side they fly on. I fly on JC on both imp and pub side, and am one of the few people that has gotten a recommendation for a character on both sides. But the truth is I am only alittle better then "average". Usually I am far better at playing some sort of strike fighter and just being incredibly hard to kill instead of being a "killer" myself.
Regardless it is a fact that playing on the Imp side of JC is far harder then on the Pub side. There are fewer premade groups, fewer people in voice working as a team, and fewer "mature" players as in players that have had time since December to skill up their ships.
I can't say much about the grunty/udezak debate, mostly cause I don't know grunty well other then his consistant flying of the same flashfire spec. I can say, with personal knowledge, that Udezak has flown on the imp side, in a teir 0 strike fighter, against teams of semi to fully geared pub players, and gotten over 15 kills. That is a ACE Pilot to me.
I am also going to put alittle shameless plug here. The Pub Guild "Alpha Strike Force" has the largest single concentration of recommended ACE Pilots in this post. Congrats to my guildmates for well earned recognition in your skills at GSF!