I usually Invest a very small amount of bitcoin to another coin because I know this time is very crucial to invest in any new coin or even in an old coin.
Any suggestion from your side which is good for long term
There is a lot of altcoins that can possibly give you a profit you need to select a good one or two, for now i think it is not too late to invest in different or top altcoins because bitcoin is just starting to rise and there is no other good option for now than selecting a good coin and hold because after bitcoin rise altcoins will surely follow.
based on my own understanding i think you are right in terms of buying and holding altcoins right now,that is a good strategy in the start of bull season, we cant deny that we are now at the start of a bull season and the start of rising of price of some good altcoins they are listed on coingecko and CMC tou can find it there and select.