It will all depend on your market. I have a townhouse in an area where it's not a common fixture. It takes longer to rent than a comparable SFH would because it doesn't have a backyard. It's "unique" for the area and unique is not always the best option for rentals. If town houses are common in your area, look at comparable rents and see what that looks like.
I have five townhome condos in addition to a triplex and a larger MF. I am finding the townhomes to be providing very good C on C returns with the least work. And, a better caliber tenant. More similar to single family homes. However, it is difficult to find townhomes where the numbers work. So, acquisition is more difficult. And, you do lose control of some of your expenses. But, I like having all of the exterior maintenance taken care of. You do need to do due diligence on the association very carefully. I have a short list of associations in which I will invest and a longer list of those where I won't.
Townhomes are great. Usually draw much higher rents than garden style apts. We've found they often attract a stronger resident/people will treat them with care & stay longer as it feels like they have their own home.
I guess the con is there is typically more space throughout so turn costs will be higher. Also, if you are buying individual units you want to see if there is an HOA & learn how that will impact your investment.
In CA HOA's can be through the roof and really cut into your bottom line. Also, if something big happens to the complex, like an earthquake you can be on the hook for your part to fix it. But, I do get a good return on mine because of low HOA.
@Kelly I. , I should have said "complexes" not "HOA's" in my comment, as my reasons go further than HOA issues. I have yet to find a HOA that requires tenant approval, but of course there can be rental caps/limits. Additionally I like to evaluate the financial health, capital reserves, and property condition of the association to try to understand whether a large assessment is looming. I also look at deferred maintenance and common charge delinquencies as an indicator of how the complex is managed. The biggest factor is not directly related to the HOA but other market factors. It seems that in my area the ratio of purchase price/rent can vary significantly fro complex to complex, sometimes for reasons I don't understand. As one example, a complex I invest in (B-) has an average acquisition cost of $85K/unit and rents for $1200/month. Just up the street is another, somewhat nicer (B) complex where the acquisition cost is about $125K/unit but the average rent is only $1300. Same neighborhood.