The most promising crypto will always be Bitcoin but in spite of that, it is still not advisable to have all eggs in one basket which means diversification of investment and the best 3 cryptos to choose will be BTC, ETH, and BNB in 60,20 and 20 percent respectively. However, crypto investment is not for lazy people and I will advise you have knowledge about portfolio management to secure your profit and to prevent loss.
Remember however,,, the dirtiest word in altcoin business (to me) is "potential" and "promise" is similar.
Every single thing you put out in the world can have promise and unlimited potential but without foundations,,, not a single one of that promise and potential can grow. Bitcoin started same as all,,, but on the foundation was something new, fresh, secure, real. A solution that many needed and therefore many used.
99% Altcoins prove they lack all this by having ZERO users.