to be on safer side, old coin like btc, eth, bnb are the sure bet. but if you would like to choose new coins, first check for newly added coins on coinmarketcap, then do some findings on the team behind the project and what the project aims to achieve in the blockchain industry, check the total and circulating supply of the coin, exchanges where the coin is trading is very important because that is what guarantees highly liquidity.
l feel also so safe with top altcoins like BNB, ETH, etc. l think there is less risk by investing top altcoins than other altcoins. But if we are looking for the best altcoin for investing in, we should realize that which one has a great team and also timely development cycles. We should focus on the project how is it going on. We must read about the project, then we can invest in the project. Every project is not as safe as expected, we should make hard research.