For short term trades, I don't look if a coin is PoS or PoW, I just look at the things I feel newbie investors will look at when they come in [by the millions]. Things like name, [cheap] price, logo design, maybe active devs and a good reputation and other simple things like that.
So if the coins I'm buying (for a flip) aren't PoS then it's just a coincidence.
Longer term, there's no way I'd ever buy and hold any coin which is not PoW AND a coin secured with massive hash power, like iXcoin. The reason is that's the single best way to secure a coin for mass, Global adoption.
PoS security is POS...pun intended, and without an ultra secure network your coin is DOA, good only for short term trading.
So far PoS coins have certainly proven to be secure. A PoW coins is basically an arms race, to consume the most amount of energy.
There are good technical papers written on this and PoW is easily the most secure choice.
We're talking about global transactions here with anyone trying to crash your network. That's where PoW gets the job done and everything else is simply another gimmick.
Call it what you may, but my money lies on a PoS coin taking over BTC and any PoW coin within 2 years. It is not just the fact that a PoW waste millions in electricity a year, but certainly faster transaction times and other features coming out of PoS coins are far superior if they stand the test of time.