I think that the best altcoin for investment is Ethereum because a lot of meme coins, DeFi and NFT use Ethereum blockchain.
Also now is a very popular Binance Smart Chain. It means that BNB is very prospective too.
I agree that it is very important to evaluate how useful is this altcoin to understand its future prospects.
But commissions in Ethereum blockchain is very high.
If commissions in Ethereum become low it will be more useful for people.