Why? I think ADA has more upside both as a long term play and from a short term gains perspective.
I don't know too much about ADA so I can't speak too much about it.
Polkadot on the other hand looks to have more adoption.
Gavin Woods one of the co-founders of Ethereum founded the Web3 foundation and thorugh that foundation they've been giving grants to loads of projects for the Polkadot Ecosystem.
Even in Coin Gecko there's a tag for DOT ecosystem to show the amount of projects building on DOT which I don't think is there for any of the other non ETH competing L1 blockchains.
They also said they don't see themselves as an ETH killer but are more interested in interoperability which is the next step for blockchains IMO.
All of DeFi is currently in ETH so by bridging to ETH you can access the liquidity of ETH in addition to what will be generated on DOT and if they improve on the scaling and high gas issues then that is a big win.
I'm glad ETH is moving up in price but the fees on Uniswap or anything with a smart contract is just unsustainable. I've been staking RAMP and I'm scared to unstake becaue of gas fees

I don't know what is taking ADA or EOS so long but DOT looks ready to go this year. Even the L2 scaling solutions for ETH like Matic and xDai are still not widely adopted yet.
In the short term, parachain auctions are happening in the first half of this year and for any of the projects above to get a parachain they need a lot of DOT and they need to lock it up for a long while which should reduce supply and increase the price. Some of them have already connected to the testnet version and so progress is looking good.
In the long term, if they are the 2nd blockchain to get a healthy ecosystem while having some advantages over ETH then I can see DOT easily going over $100.
For the projects that can't afford a parachain, there's Kusama which is basically the same tech on DOT but with a different governance system.
The ecosystem and timeframe is what makes me the most bullish not just the tech.
If it was for the tech then I would look into Elrond and Solana which have been generating a lot of buzz, especially Elrond.