Any alt coin suggestion expect ada.In my point of view of ada still can't surpass ETH in the smart contract field and even if they can make it will be hard to be replace existing eth smart contract eco system.Moreover late coming project like sol even surpassing to ada,all things ada have is the loyal user base and nothing special things in tech
If you want to gamble by choosing any altcoin, then i do recommend act wisely.
Choose the coin with high marketcap.
These are the coins that have more chances to give good profits in long term runs.
If you are seeking people’s suggestion, then go for some paid calls if possible.
I do say rather invest on ETH and LTC for long term.