Interoperability, security, and scalability: Which blockchains have the most promise in each of these areas?

Interoperability, security, and scalability. Imo, these are the biggest "elements" of the blockchain universe and this also where the greatest challenges and opportunities are. Now, the question is: in your opinions, which blockchain(s) is/are currently best-equipped in the area of interoperability, security, and scalability?

I'll kick it off:

Interoperability -> Polkadot and Tendermint

Security -> Cardano

Scalability -> Ethereum and Cardano