Personally I prefer a PoW+PoS hybrid like Dash and several others which came later. The Masternodes control the governance while miners secure the blockchain. If pure PoS is like winning in a democratic election, Attack on Dash would be winning against Hitler.

1/3 of circulating supply is already in masternodes and masternodes take all the decisions in the DAO. In PoS every coin holder matters. In Dash you only matter per 1000 Dash owned. If someone create a mining attack, masternodes can immediately take action. If somebody tries to take over masternodes, decisions can be made almost real time as there are only ~4500 masternodes present. So the response time for a PoS attack is much lower.