Interesting discussion!
My experience
a) Paid apps:
- Good: Samsung App Store, Amazon App Store, Google Play
- Waste of time: others
b) Free apps:
- Good: Samsung App Store, Google Play
- Fair: Amazon App Store, GetJar
- Waste of time: others
I agree on the issues about Opera (incoerent counting) and SlideMe (questionable competence of reviewers).
I also had a bad experience with InMobi (service similar to Codengo, now shut down) where they claimed to be able to submit to a lot of stores but the process of approval was a pain with poor results (delayed, bad or no app appearance in stores)
How did you signup to Samsung? I've tried several times but they kept asking me for something (like a reference) that I could never figure out.