I vote both. I invest in individuals stocks and my wife has a 403b and we invest in RE also. I'm not really interested in waiting 20 years to retire though, I feel I can make it happen much faster with REI. I've put 100's if not 1000's of hours in educating myself in both the market and REI.
If both took equal effort and had identical returns I would choose the stock market, I find it more intellectually stimulating (when investing in single stocks) and I don’t have to deal with people, tire kickers can be exhausting!
You can't directly compare the two due to effort involved, but I feel I can control short term gains much easier in REI (buying under market, value add) vs trying to time the stock market consistently (good luck with that). Yes, occasionally you can buy a stock at the right time that skyrockets but good luck doing that year after year. I love the BRRRR strategy, the thought of "putting a down payment down" and waiting 10 years to make that back in cash flow doesn't interest me.
My wife and I are in a good position in that she works a 9-5 that makes more than enough to cover our nice life style. I do the investing full time and take every penny I make plus my wife’s extra income and put it right back into investments. I dont use cash flow for life style, it goes in the bank as reserves or into the next investment.