There things that you need to consider when comparing the two investment mechanisms. Allow me to shed some knowledge to you:
Firstly, stocks are an investment alternative wherein you acquire shares from a company relative to their sales and success. You may either profit from the shares of stocks when each share increases their price or lose money when the shares lose value. Be also reminded that stocks are regulated by the government through the Securities and Exchange Commission (SEC) which prevents companies from abuse and manipulation of prices.

On the other hand, cryptocurrencies are generally something that is very volatile in price- wherein the price of one bitcoin (or any altcoin) today might be higher/lower compared tomorrow. Its high volatility makes it an investors favorite in terms of short-term gain by taking advantage of the said nature. Be reminded also that no government entity regulates bitcoin. Due to this, some countries have banned and prohibit the utilisation of such (subject to the laws of your country).

Now the question is, what is the preferred choice?
The answer is- it depends on your financial capacity and status as an investor. If you have the sufficient capital, then you might want to invest into cryptocurrencies and hope that its price increases. In order to lower the risk, one must be updated about the recent news and updates regarding crypto because it is very controversial among large trading companies. For stocks, typically people invest into these for long-term gains. There is also the presence of a collateral which makes it safer compared to bitcoin.  
Personally, you might want to diversify your investments by investing into both stocks and bitcoins for profit maximisation.