My opinions: There are not meaningful differences between different proof of work coins. All PoW is based on the same principles, has the same security costs,

My opinions: There are not meaningful differences between different proof of work coins. All PoW is based on the same principles, has the same security costs, and the same scaling challenges. Bitcoin remains the top dog and will likely stay that way due to network effect. PoS could be interesting, but it's largely untested in the way that Bitcoin is. We need to see how mineres/voters behave and whether large holders can exert undue influence. Ethereum is by far my favored coin to see this tested, and if successful, would actually have more security for a given network cost. This is potentially disruptive. DAG-coins or whatever you'd like to call them seem to like they're getting 'free wins' and I suspect that their security model is not sound. They're interesting but extremely risky. Ripple is simply not a cryptocurrency by any reasonable definition.