Bitcoin and Etherium are one of the best coins for long term profit. These coins tend to operate the market. The market is hot right now. So if it falls, you can convert it to USD. You can make a lot of profit by investing in other coins but there is also a risk of losing your capital. You can start trading. It will help enhance your experience. And as your experience grows, you will try to make a lot of profit.
BTC and ETH are one of the best coins to stay invested for long term. Bitcoin being leader will the first to move upwards and rest of the altcoins will follow bitcoin. ETH is market leader of altcoins. And it is almost half from its ATH. So can expect a good move in this coin in 2021. I would also recommend buying BNB as this is favourite of many investors. So can buy and hold BNB too.