The main advantage of asics is that they can't be used anymore after the attack is done and they are just a worthless door stopper. Or at least their worth would be significant lower. ETH uses GPU (graphic cards) and you can still sell them later (until better ones are out), so an attacker would have a much lower loss compared to asics. This advantage is also a disadvantage for normal users because asics are almost worthless after they are outdated or broken and can't be sold anymore. Their only purpose is mining SHA-256 algorithm. Maybe thay can be recycled for precious metals. So both ETH and BTC PoW have advantages / disadvantages.
But for security reasons to protect the network against 51% attacks the BTC PoW is a better solution.
there is no difference between bitcoin's PoW and Ethereum's when it comes to things like ASIC and hash power,... and i think you are confusing ASICs with bitcoin-specific-ASIC.
an ASIC is an application-specific integrated circuit, think of it as a CPU that instead of doing general work is modified to do only a specific work. for bitcoin ASICs which you are talking about, this "work" is to calculate SHA256 hashes. but it doesn't have to be, it can be anything else but you have to create a new machine. for example we have Litecoin ASICs that are designed to compute scrypt hashes. also recently Bitmain released their ethereum-specific-ASICs called Antminer E3.
so what you are calling advantage here is just ethereum being far behind in the evolutionary stages that bitcoin passed many years ago when the first ASICs for bitcoin were created.