The major benefit of ETH over any other alt, I would say is that adoption is higher than most other alts. Even though it's not really used other than ICO purposes at all, almost all ICOs do still use the ETH platform to host their tokens, which is huge.

That doesn't mean that ETH is the best bet over the long run at all, I think that there are plenty of better options out there.

However, ETH is simply serving way too many ICOs right now to be out of the top 3 altcoins, in my opinion. As long as ICOs are still a thing, ETH will be used on a wide scale and value won't tank.