I use BC. The interface is easy and setting up campaigns is easy. But you have to be careful with your settings. If you leave all the settings on and target just the tier 1 countries, you still get a lot of other countries which is not good. If you uncheck the Blackberry setting, this improves the results a lot but reduces the traffic significantly.

The other major variables is the copy in the text ad and your optin form. I have found the image ads to get less optins which includes the cost to a subscriber.

Be prepared to do a lot of testing.

Looks like bots they say

Is BUZZ CITY a SCAM?

Did not use them yet, if i want to spend money, i will try FB

i have never used that one, but there are no good suggestions about buzz. maybe it works for you!