Alright, now for a bit of commentary:
I'm honestly surprised that the love is not there for the ol' Dreamcast crowd! (I must admit that I have a huge soft spot for that cast). Strangely enough, I never quite got into the 4kids cast, and I specifically recall a nine year-old me being quite upset upon realizing the change when I first played Shadow the Hedgehog.
I absolutely loathed the change at the time, and perhaps my butthurt still remains after all these years; however, while I still consider the group my least favorite cast, I cannot deny that among them are some of the best for the roles. Mike Pollock, as many of you have already mentioned, has become the definitive Eggman/Robotnik, and captures both the silliness and seriousness of the character all too well. I grew up with Bristow, who also was great, but Pollock has to be my favorite these days. The rest of the cast I could never get into. Dan Green is an awesome voice actor, but I found his Knuckles, while good, never seemed to have that 'coolness' the Scott Dreier Knuckles had. Jason Griffith's Sonic has ultimately grown on me over the years, and I can concede to the fact that he may very well be the best of the bunch as Sonic. He comes of as both light-hearted, but can be taken seriously at the same time. I ultimately like his Sonic over his Shadow, who comes off as a tad too dramatic at times, but his performance is far from bad. I still stand by the notion that David Humphrey's Shadow, specifically in Heroes, was the best one. Other than Green, Pollock, Griffith, and perhaps also Amy's VA whose name I don't recall off-hand, I cannot say I'm a huge fan of the rest of the cast, especially Tails.
I ultimately enjoy the newest cast the most mainly due to the performances being solid all around. I know there are many who loathe Roger Craig Smith's Sonic, but I actually find his take all right. His voice isn't the best for the character, but I think it's the way this Sonic is written that aids RCS's performance. It sort of reminds me of Jaleel White's Sonic in that he's a bit of a joker. I think the Tails VA's we've had in the new era have been the best two voicing the role, and Travis Willingham's Knuckles seems to find the right balance between Scott Dreier and Dan Green.