The best investment option involving Bitcoin is.... Bitcoin itself. Bitcoin was originally intended to be a currency. But nowadays, it is mostly behaving as an investment asset. And I would advice every one to stay out of the other Bitcoin-linked investment options, such as crypto-stocks. Most of these schemes are ponzis, run by conmen.
I think bitcoin is not the best investment anymore. Look for new potential ICOs, that has a growth chance and big idea like
Zamanat Ride & Safety, which is something like Uber but with more great use cases like security and using blockchain to store data as well as end-to-end encryption...