You will expect that many people will recommend Bitcoin as this was the best option.
it is not all about being known to the crypto market but it is a matter of how this coin is worth in the future. Imagine that from $0 and it continues to rally that it reaches $60k last Bullrun, it probably there's more it happens to Bitcoin.

But being considerate of the risk in investing in Bitcoin alone, it could be wise to split investment to altcoins.
You can find a lot of them https://coinmarketcap.com/. Just do the search first and I suggest looking first at the old coins.