I have used American Home Warranty on my rentals for the past 20 years. The older the house, the more you might consider a home warranty. The cost I pay is $85 per visit. The cost of the yearly warranty is around $400-500. On the plus side, they do numerous common repairs, but you must read the contract to be sure it is paid for and you can add "extras". My one rental property duplex is 86 years old AND it is located in the mountains. Just the fee for any company to drive to the house is usually $50-$75 alone so the warranty company saves me money right there. Many regular contractors will not even come to the mountains... AHW have paid for new water heaters, , propane plumbing, washer dryer repair, as well as replacing other appliances, such as a refrigerator and a dishwasher. In one of my homes they installed a new heating system that only ended up costing me $800. Another I had an entire stove top replaced for free, minus the $85 fee. It has been a blessing to me as it is difficult to find a reliable handyman and I am not much of a do-it-yourselfer AND they charge one fee for both units.
On the down side, sometimes they have shoddy repair companies. I usually look on Yelp before they send someone out for repair. I have been working with them so long I can navigate some of the resistance they can put up for fixing things as well. If I can, I ask not to use that company and they will accommodate my request most of the time and find someone more reputable .. Also, they sometimes add fees. For instance, when I had a water heater replaced, the company charged me $400 for the added cost due to the fact it was propane hook up.
Further, there are long waits to get a hold of the company and I find myself having to follow up with them many times but I try to push this on the tenants as much as I can. That way they can have some flexibility over the situation and be home for the repairs.
Overall, I have been extremely happy with using a warranty company. It can be a real headache at times, but overall it has paid for itself many many times over the years.