Personally, I'm in 2 minds about POS vs POW.
I love the idea of getting rid of "wasting energy".
On the other hand, it's that "wasted" energy that gives the token additional undisputable value and is therefore a great layer of trust, next to the current trade prices on the exchanges.
Same effect as with gold. It's expensive to mine, hence it's rare, hence it's valuable. In theory, there should be some market-driven self adjustment happening to how much energy a coin consumes and I think that's what's happening. So POW isn't necessarily bad. Also, there are many voices warning against pure POS as there seem to be some issues with that, too.
I've thought about that topic a while ago, too and my feeling is that a new POW/hybrid POW/POS approach that somehow incentivizes contribution to coin network health might be a good approach. E.g. instead of just having the tokens "at stake", the POW part could be about providing network bandwidth (e.g. forwarding new transactions) or transaction history lookups. I'm not sure yet how to encapsulate these tasks in a way so that it can be verified independently that a node has done it. But it must be possible, SETI@home is somehow verifying processed packages as well.
The POS part could stay more or less the same as having tokens at stake I guess.