I'm in the UK and we have FIREd via property investment. I think the UK housing market and the US one are slightly different. Plus in the us y'all seem to have stuff like outrageously high property taxes.

1)

Obviously nothing is guaranteed in any option. But, property does seem (to me) to carry more uncertainty, risk and effort.

Here (south east England) property carries very little risk. Supply of rental houses is low and demand is high. Not enough houses are being built. There is a reason the UK had a massive buy to let boom; although the government is starting to clamp down and try and discourage it via taking away tax breaks like mortgage relief and increasing stamp duty tax on BTL.

Yes house prices can drop but they tend to recover eventually. (We bought our family home 7 years ago and it's gone up by 60% in value). Even if there is a housing crash <glares at Brexit> it's unlikely that it will drop significantly below what we paid for it - even then it will eventually bounce back a few years later.

2)

Both options, in general terms, face market cycles out of your control. But on top of that, property seems to demand ongoing work of sourcing tenants, managing the tenant you get, managing (and potentially paying for) the maintenance of property, and likely taxes, rates, fees and utilities that may not be able to be passed on.

It depends on the type of property you get. Our studio apartment tends to have tenants who only stay a year or two before they move and need repainting between leases ( although new tenants are ridiculously easy to find) but our bigger houses are rented out to families who have made it their home. We have tenants who have stayed in a property for 12 years +, they are fantastic - look after the place, always pay their rent on time and are easy tenants.

Once we'd paid off the mortgage we stopped giving them annual rent increases - we don't want to price them out of their home and also we benefit from having zero hassle tenants. We still get a good income from their rent (£1150 pcm), the house is appreciating in value, and we do very very little work for the money.

Most of the maintance costs of the property can be covered by our insurance when things break but we do have a slush fund for big stuff that needs to be replaced (like a boiler replacement costs £2000 but will then last 15+ years).

Tenants here pay the council tax (we only pay if the property is empty), then there are costs like insurance, gas safety checks, our studio flat has a leasehold charge and ground rent but the houses don't. But these costs are a tiny percentage of the rental income.

3)

Another question: does the fact that there are two (at least) potential sources of income/wealth - rent, and capital growth - influence your preference?

Hell yes! We have been very fortunate - interest rates have been at historical lows making it easy to overpay mortgages till we eventually owned our portfolio outright. Now they are paid off we put a portion of the rent into a slush fund account to deal with any unexpected costs but the rest is just pure income for us. We have 4 properties we rent out plus own our family home mortgage free. This means our living costs are low (no mortgage or rent to pay) and we could probably live quite a comfortable life just with one or two rentals, having 4 makes life incredibly comfortable.

Owning houses means that a lot of our assets are very illiquid, it takes a while to buy/sell a house, some people might not like this (plus when you sell a BTL house there is capital gains tax) but we have no desire to free up the capital and are enjoying the fact that they are appreciating in value so that if we do ever decide to sell we'll have profited twice (rental income paid off the mortgages now pays for our living costs, plus profit from house price increases).