If you want to make long term(2-5 years) investment - bitcoin the best choice. But if you want to make short term investment you must look at fresh and undervalued blockchain projects which can make x10-x50 on the next bull run. Try to research teams, roadmap and possibility of projects like: PCHAIN, Fusion, Fantom, Eximchain, Aergo and others.
But make your own decisions. This is not financial advice.
Interesting projects if they fulfill their plans as described in the White paper. The big drawback - illiquid exchange, so you can lose money. It is better to invest in time-tested altcoins!