A lot of technologists seem to think that the big divide is between proof-of-work and proof-of-stake. And then they encounter creatures like Ripple, BitShares or AlgoRand and get confused. But the PoS/PoW only applies to eventual/asynchronous/non-finite (slow) consensus models, and other methods are in use for synchronous/finite (fast) models; in fact PoS is used as the basis for voting in quite a few fast consensus models, making it all more confusing.
To try to make sense of it all, we had a short presentation about consensus models in Kik TLV office.
The slides:
complete video: