it is a matter of experience. you can't say which one is better than the other when it comes to trading. they both have pros and cons of their own too. for example bitcoin is more volatile while it is more profitable. but stocks are less volatile and less profitable while at the same time they have risks of dropping hard like these days.

for someone who has spend years in stocks market and traded them so he has a lot of experience: stocks

for someone who has spend a long time in bitcoin market and traded bitcoin so that he is familiar with how it works: bitcoin

for someone who has no prior trading experience and has never been in any market: neither!