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...
Bitcoin might not be in the early stage anymore but it has a lot of potential that it will rise.
I believe in due time we will see it very profitable, so far I can say that it's profitable as it has deliver a lot last year and this would be a challenge.
Growing your money 100% every year makes bitcoin already a good investment and that is only a conservative estimate.