What is Machinima's contract for you? I mean, in terms, how long is it? I heard that it can be really bad? It used to be the general "Gaming Channel's YouTube dream" to get partnered with Machinima because they really are the ones that revolutionized the gaming aspect of YouTube and put out a lot of commentary videos. Everyone wants to go to them just because of the name, "Machinima." Recently, I have heard a few negative things about them. For them, it's really all about the numbers; subs, and views on your channel. They just want more money. A lot more newer networks, are actually looking at your potential, quality of content, and can provide you a better service with better support because they are newer, and trying to emphasize on the areas where gaming networks like Machinima, lack in. RPM/Maker Studios: I have heard good things about them. They are one of the biggest networks, next to Fullscreen. So they get pretty good adbuys. Machinima should get pretty good adbuys as well since they are the biggest entertainment/gaming channel on YouTube.
So really, it's up to you. With RPM, you could see how the network is for 1 year, then later choose to go with Machinima. I have spent a good month and a half researching many different networks so I encourage you to do the same before making any decision!