I would prefer to buy property any time. People will always need housing. So while the price of the property is pure speculation, rent is a nice steady source of income.
Only if people want to live where you buy the property. If you bought property in Detroit in 2005, how much rent would you have collected in the last 15 years?
This is true, but it's worth considering that investments in individual stocks or in index funds (I would avoid actively managed funds) are incredibly liquid.
If I decide the housing market isn't for me or I need to raise cash quickly, I could be forced to wait anywhere from 8 weeks to 18 months, or longer to get any of my investment back (even longer if I don't want to lose money through desperation to sell).
If I need to raise money from stocks or index funds I can get market value for those investments instantly during business hours.
Assuming you had no property, would you be comfortable with your first purchase being something you can't yourself live in? Also, would owning mean a huge time investment maintianing it?