There's no need to pick one, you can just buy both. If I had to say one I'd go with Cardano, but that's just because I've never fully trusted EOS because of the nature of their ICO. There is absolutely no need to generate that kind of money just to fund your project, it leads me to believe that the funds are for self-enrichment rather than for the project itself.
But that's just me. Both are high-profile and claim to offer solid tech, and both will probably remain near the top in market cap.