If you had to choose one stock, and only one stock, to secure your financial future, what stock would it be and why?

We were discussing the other night Warren Buffet's methods of finding a good company and basically sinking a lot of money into that one investment – Buffet's reasoning is that this is less risky than diversification if you have confidence in that company and you know all there is to know about that company and management. The regular companies of course came up in our discussion: Amazon, Tesla, etc. Do you have a more obscure one that is not necessarily making the headlines now that you would bet your financial future on?

Very interested to see what people are focusing on. More interested in hearing about individual stocks than ETF's or god forbid, mutual funds, yuck.