I've only used the following:
- palnet
- steemace
- neoxian
- steemleo
- battlegames
- splintertalk
I've been receiving my tokens and I've been staking every single one of them. Like alt coins and ERC-20 most of the new tribes will become mostly wastelands and will be worth next to nothing. But do I have a crystal ball to tell which is which? NO!!!
PALnet will do really well. It's basically the standard for everyone else. I lot tokens airdropped because I owned PAL. The safest strategy is to stake them all and wait. If you are brave you can get into speculation. The best part is that each tribe can become an experiment layer to try things out before adding them to STEEM. It's also empowering way to get people into making their own social media for a niche like subreddits.