Is it a good way to choose lots of ad networks in heyzap network selection part? Or it is better to choose 2-3 ad networks? Which one do you prefer? In my game there will be rewarded videos, banners and interstitials.
Depends on the success of the game but I would start with just a few. Earnings are paid out by each individual network and they all have a 100 dollar minimum payout. So you don't want your revenue spread around a lot of networks.
I always prefer heyzap. Heyzap is a social discovery and monetization platform for mobile games and apps.