DOT vs ATOM

I have recently decided to try and branch out from the two main cryptos I own (BTC and ETH). While other projects have recently caught my eye I have decided that this time I would like to focus on blockchains that specialize in scalability. Since I came into some unexpected crypto via an airdrop and since then have not touched it yet want to move out of the token I wanted to first come here and see what people thought. It is my understanding that the two leaders in this scalability space are Polkadot and Cosmos (DOT and ATOM). Before I deep dive into the two I wanted to see what the community here thought about the two and which blockchain would you want to invest in and why would that be?