ADA and SOL are similar in many aspects, but the area where Cardano beats Solana is security. Cardano’s verified proof of stake mechanism is proven to be better than, not only Solana but also Ethereum. Cardano’s Ouroboros Proof of Stake mechanism has helped the blockchain run on 99% less energy than it would without it.
The Proof of Stake system also added low transaction which is an attractive point for any investor at any point in time (transaction fees are reported to be approximately 0.1 ADA) which is still higher as compared to HBAR’s 0.0001 HBAR, but given the security attached to it, it is a good bargain.
The place where Solana lags is due to its outages, it has experienced many outages which left the blockchain frustrated with backlogs of transactions to complete. Solana seems to have focused more on scalability rather than security which is the opposite in the case of ADA.