@Tom J., I invest in both commercial and residential real estate. In my opinion, neither is 100% superior over the other as they both have their pros and cons. I believe the best choice is to diversify into both.
Commercial can have fewer management hassles than residential, but it also can have much more. For example, if you invest in triple net leases with the tenant is responsible for everything (maintenance, taxes, insurance, etc.) it can be very easy to manage. On the other side of the spectrum is something like a hotel, which not only is a real estate business but also a convention/conference business and restaurant business. Those can be a lot to manage. So it's impossible to generalize.
As far as cash flow: again, it's not accurate to say that one always has more or less than the other. You can find plenty of residential deals that will project a higher or lower return than commercial, as it depends on the amount of leverage, the strategy, the place it's located in, the class of the property, etc.
Residential real estate:
1) Generally cheaper than commercial real estate, which allows smaller investors to purchase properties on their own and participate.
2) More cycle friendly. At least on a diversified, nationwide basis, residential real estate prices very rarely drop. In the last hundred years it's only happened twice: Great Depression and great recession. In contrast, commercial real estate prices are very cyclical and tend to drop every 18 years or so.
3) Much easier to sell, because not only are there other investors to purchase, but also people wanting to live in it. Commercial real estate can only be purchased by other investors which is a smaller pool.
4) Requires less specialized knowledge (as some has mentioned above) because most people understand residential real estate from owning a house. Commercial real estate and other hand can be very specialized and require specialized knowledge.
5) Can be a positive or negative: the price of residential real estate is based on many things that have nothing to do with the value of the property as an investment. This can mean that it's more expensive than it needs to be for investor, or it might mean that the investor can pick up a bargain. In contrast, commercial real estate is priced based on its income generating potential. There are some small modifiers, but it generally never gets out of whack from that value, like residential real estate does.
Commercial real estate:
1) generally generates more cash flow per square foot than residential
2) leases are much longer (other than apartments) and can last five to as long as 20 years. This can be a much more reliable income stream. Residential real estate leases are generally one year and so there is more tenant turnover and management expenses.
3) more variety: you can invest in everything from multifamily to retail to industrial to office to hotels to mobile home parks, etc. Each has their own unique risk profile, so it may be a better customized fit in your portfolio.