Well, I have always had good luck with Overture. What I have found is you NEED to have highly targeted words to keep your conversions up. Clicks are great, but the conversion is the bottom line. Although, because they power about 80% of the PPC marketing, they do tend to be a bit pricy for those broader phrases.
Looksmart is another I have had pretty good luck with. They have receintly aquired a very smaller name engines that power a pretty decent amount of traffic, with very little conpetition. I started with the inclusion part of Looksmart, but after having a fairly low ROI, I decided to drop that and move on to their keyword campaign.
I am also running an Adwords campaign that is ok, I guess. About 2 months ago I was about to drop the campaign, due to the high cost and very low conversion rate. But a couple of weeks ago there seemed to be a drastic raise in my conversions, granted you are not doing the braod targeting.
The others you listed, I do not have that much experience with. I just figured I would give you what I know. I hope this helped.