Full disclosure: I also sold most of my ETH to buy ADA.
Anyone who has done a deep research on ADA knows it's a screaming buy. It's not even fair to other altcoins to enumerate why. But here are a few reasons:
1) When the IELE VM is released, that will enable developers coming from
about 20 imperative languages (see
https://github.com/kframework) to write smart contracts in, so in the language they are the most comfortable in, and it will translated to be readable by the Haskell protocol. Backward compatibility.
That's a lot of potential developers if you ask me. Ethereum will look like a toy when it's released this fall (and I hold some).
It's built by RunTime Verification, a start-up from Uni of Illinois who has NASA, DARPA, Boeing, and Toyota as clients. They now work for Cardano / IOHK. Not exactly kids in their garage. I don't see how it can go wrong....
https://runtimeverification.com/blog/new-technologies-for-the-blockchain-iele-virtual-machine-and-k-universal-language-framework/2) Their Sidechains protocol will make them the blockchain of blockchains when they'll finalise NiPoPoW and NiPoPoS. That means that they don't intent to replace anyone, but rather to enable every blockchain and ERC20 tokens to talk to each other
https://bitcoinmagazine.com/articles/sidechains-why-these-researchers-think-they-solved-key-piece-puzzle/3) High Assurance Code used by Nasa and Plane manufacturers, this is the kind of code used in life-or-death situations....
https://www.youtube.com/watch?v=TZGVgNsJSnA&t=164s AND
https://www.youtube.com/watch?v=mhKUHpQZIoc&t=4) Why Haskell is hot for cryptocurrencies? Because it eliminates a whole class of bugs compared to imperative languages (that's why they hired the co-inventor of Haskell, Philip Wadler)
https://www.fpcomplete.com/blog/why-haskell-is-hot-for-cryptocurrencies?hs_amp=true&__twitter_impression=true5) Everything is peer-reviewed and audited by the best cryptographers from top universities and third-party auditing firms, which means that unlike EOS' outlandish claims on hundreds of thousands of TPS, everything Cardano claims is actually true and verified.
6) Multicurrency Daedalus Wallet ( BTC- ETH- LTC- ADA etc...), an extremely well-polished wallet, possibly the best in the space
https://daedaluswallet.io/7) I could go on...
2 testnets are released next week, and PoS and Staking are released in a few weeks, which means you will earn interest on every ADA you hold.
A screaming buy. There are no other projects that even fantasise about what Cardano and IOHK are achieving.
From a monetary point of view, OP has WAY more chances to do a x5 or x10 on buying ADA at $0.25, than holding ETH. ETH can maybe hit $7000 one day but not this year, while Cardano already hit $1.33 in December 2017....
EDIT: corrected some spelling errors.