Usually they provide you with some free music from companies they are sponsored with. They will also usually pay you monthly through paypal so you don't need to wait to reach $100 through adsense. They also usually have community forums where you can collaborate with others and share your content for others to see. I'm with Freedom so for example they often post helpful tips for youtube channels and they feature a couple channels everyday on their youtube series. Also sometimes networks offer sponsorships with youtube channels that get a certain number of views and they can receive games, gaming gear, etc.
Instant video monetization (you don't have to go through YouTube's review), usually they have community forums which are pretty good to hang out with other partners and possibly share your videos, ask for tips etc. And depending on the network, some have more advanced dashboards, others have bigger audio library, some are partnered with TubeBuddy so you get Star level access to that great extension for free as well and so on... Just don't expect growth from network and you'll be fine.