1) Decentralization is a spectrum, BTC -> ETH -> SOL, AWS will be really difficult to get some blockchain properties: permissionless & composability.
For smart contract platforms, imo some level of decentralization can be sacrificed for higher throughput, read more here: https://haseebq.com/why-decentralization-isnt-as-important-a....
2) ETH will be more secure than Solana! Solana requires both higher bandwidth and a beefy machine[1] to run a validator node.
https://solanabeach.io/validators
3) Polygon is both less scalable & controlled by a multi-sig(less decentralized) which is also similar to BSC. Polygon is based on EVM, Solana is BPF/Rust based with some unique set of optimizations like Sealevel[2] which enables parallel processing.