When you look at the costs for mining PoS vs mining PoW coins as a percentage of the value of the total coins then PoW is much more efficient. PoS actively discourages people from spending their coins therefore the economy will never mature and thus the value of the coins will always be small. This will result in the PoS coin always having a smaller potential market cap then any PoW coin to the point that the cost per dollar of market cap is higher for a PoS coin
This is not true as there are versions of PoS that it doesn't matter how long you hold the coins. Delegated proof of stake for instance destroys fees and that is how the companies dividends are paid, thus it doesn't matter how long you've held the coins or if you buy something with them. BitsharesX is one of the very few coins that is truly deflationary at this point in time. A lot of coins claim to be deflationary... cough... Bitcoin... but they will be inflationary during our life time.
I am 100% with the OP, PoW is not the best solution to decentralized consensus any longer due to numerous reasons.