Well...one that comes to mind off the top of my head is Liberallarry. While I certainly don't agree with his positions, I've never encountered any of the vitriol that I have seen with others. Another one may be Logsoul...only because he seems to take contradictory positions on just about everything. He was a big Plame defender...and while I had a long, heated debate with him, he stood by his position without resorting to namecalling. Thankfully, the abusive ones don't last long.
Hmmm...wasn't aware liberallarry existed. Interesting. Thanks for the info.