I think that both projects are going to be alive for the time to come, if it is a good investment? it depends, if the strong speculative period is over, we will see the real market value, based on business usage and capitalization. Of course there will always be a bit of speculation, but now we are far from being on earth&rational.
Being said that, I think that ADA have to prove a lot, as someone said, ETH is mature so we know what it is capable of. However, as we all now, once you are mature changing is more difficult. Therefore, ADA has a little adaptive advantage, they can still design themselves around the new needs in the blockchain space. However ETH is proven to be working right now.