There are a lot of different dimensions along which these can be compared. First, both PoS and PoW can be used in leader election for pBFT and Bitcoin-NG.
- Transactions per second could be the same in both cases. There’s nothing inherent to PBFT, that makes it faster as far as raw transaction throughput is concerned. It could even be argued that in theory Nakamoto consensus should be able to churn out more transactions.
Now if we talk about confirmation latency/finality, then PBFT would be a clear winner.
Again, it depends on how you look at it. Let’s consider:
- Initial friction: acquiring staking rights versus computers. That is, accessing an exchange to buy cryptocurrency or getting a computer with graphics card. Both cases would probably require setup of some software. Not sure which approach wins here.
- Operation: setting up mining hardware—not on a huge scale—is fairly painless and doesn’t require much attention, especially when using a mining pool. At scale things definitely get much more complicated, both for PoW and PoS.
Operating staking software can require a significant amount of administrative overhead, setting up and maintaining redundant setups, to have no downtime. When slashing of stake is involved, then even more care needs to be taken that no punishable mistakes are made. Now if stake can be delegated, or similar, then it makes things much easier for the end-user. - Payouts: given that these are probabilistic processes, payouts will exhibit similar characteristics, different schemes have varying variance, which is mostly remedied by pooling/delegating. That being said, without
Most certainly, but then some people will argue that PoW encourages to find cheap/establish cheap and sustainable energy sources and will find a price equilibrium somewhere. 
It seems like it but again there is a lot to this. Is it easier to buy up stake or buy and deploy hardware? Or maybe loan stake in a trustless manner vs. hardware? Use DAOs to automate cartel formation?
If the attack ruins the network, will the stake or hardware be more worth for re-sale?
If the attack does not ruin the network then stake will most certainly be the better option, since an attacker would lose (almost) everything.
Which brings me to probably the most exciting aspect of PoS: punishment can be done on the protocol level and much more gradually. If I misbehave with PoW then nobody can just come and take my hardware—well not yet anyway ;)—but with PoS the protocol has mechanisms to punish me.