Depends on how sketchy and what I'm paying for it. Also, is it the sketchyness that you like better, or is it that they seem to have more energy in them? I find many artists don't like how they handle the transition from a sketch to line art.

I guess i find the sketchyness does tend to mean the drawing has more energy in it.
and also there are varying levels of sketchy, from very to only slightly.
http://www.furaffinity.net/view/4509550 <---id call that neat sketchy.

but i dunno, do people want clean lines if they commish an artist?

When I commission it really depends. I prefer neat sketchy with color over lines with no color. However, sometimes I get lines instead since my character is fairly colorless, but most people don't offer colored sketches of any sort, just sketch, line and full color. This means for me it's usually a toss-up between lines and full-color, and like I said, my character's fairly colorless, so the lack of color doesn't affect it too much...