Disclaimer: I work on Vitess.

I'm actually a fan of TiDB and Cockroach. I've met engineers from both, and they're super-sharp.

I am biased towards something like Vitess that builds on top of existing tech. The main advantage is that we can push-down the work to the lowest level, and leverage efficiencies that are already built in MySQL.

But the newer architectures offer better consistency models. Some customers may care more about that.

In the long run, I think these trade-offs should converge. Overall, any NewSQL is a better alternative than using traditional key-value stores, because it gives you better functionality while not giving up on scalability.