You really know what we will answer but at the end, you've mentioned that you don't want to divide into both. Well, if you can change your mind, that's what I am going to say to you. Why not just choose both of them? Buy Bitcoin and hold and then buy the stock that you want to hold since you want to have a stable return through it. But I tell you, not all stocks are going to be stable, they're also as volatile as the crypto market but not that volatile at all. Learn about what you truly prefer because you have posted and asked on the Bitcoin forum and you know that all if not majority of us here are into crypto.
I quite agree with you and say that OP should think towards diversification, and that’s investing into bitcoin and other digital assets too or physical assets. But if OP is bent on taking just one then my answer is to go for bitcoin. Bitcoin is not complicated as stock which you might have to find the right one to invest. There are stocks that can easily go down to dust, something that I don’t see happening with bitcoin at the moment. When we talk of bitcoin people easily associate it with its volatility, bitcoin has shown in the past two years now that it is getting less volatile which is the only advantage that stock had ahead of bitcoin. But for safety reasons I will say diversification into both is better