Can you read or search forum please? This thread exactly being recreated every week on this forum -__- http://www.blackhatworld.com/blackhat-seo/youtube/666534-best-partner-network-gaming-channel.html
Well machinima is pretty bad because they have bad split for nowdays just 60% for you and also lock in contract which won't allow you to leave network at any moment. I suggest you to take a look at Curse aka Union for Gamers. They have a non-lock-in contract, the best split on a market (you got 90% of your income), giving some beta keys etc for partners.
And yeah OP is asking about the network that have best CPM\RPM. I must say that these thing is useless for you. Your earning will mostly depends on the country of viewers - most payed views is USA and Australia then Europe, Russia etc. However most of the networks will take about 40% of your earnings so take a look at the one that I mentioned above.
