Generally speaking, the tokens you receive as a bounty are relatively unknown with extremely low marketcaps. This means they will only be listed on the smaller exchanges. It's hard to tell you which "Token exchange is the best" because oftentimes you have no choice (coin is only listed on one exchange).

A couple exchanges that list smaller marketcap coins include: EtherDelta/ForkDelta, Cryptopia, and Yobit. The best way to check which exchange has the coin listed is by asking the developers, as they are the ones that make the initial push to get listed.