I consider Daniel a safe columnist: never awful--which is a huge step up from Abby, Harriet, etc--but never brilliant. You could probably substitute half of Slate's writers into the job and get roughly the same output. I find myself skimming Daniel's responses because I'm so sure I know what he's going to say.

Carolyn, in my opinion, is riskier but more insightful. I disagree with her more than I do Daniel, but her columns sometimes teach me something about how people think and interact, which for me is the best part of advice columns. YMMV