Well...this is a really difficult question you ask.
Are you sure they're strays and not someone's pets?
My thinking on this subject is... if you're willing to trap the cats and have them spayed/neutered and vaccinated and then re-release them, then there's no harm in feeding them. But hubby's right. Putting out food and water will most likely result in more cats turning up. I don't know anything about the neighborhood where you live...
...but Gary and I live in a farming community. We were aware of three wild cats, one of which was a lost pet. Then the feral kittens turned up, and we started feeding them, then putting out extra bowls of food... by the time we were done, Gary had trapped about 28 cats. We have an active colony of 11 (that we know of). They're all spayed or neutered and have been vaccinated, and will be trapped to get vaccinated again this year. We actively feed and care for them. They are wild and not pettable.
The problem with feeding ferals or strays in a community, IMO, without trapping them to get them spayed, neutered or vaccinated, is that they can pick up or pass along disease to the local pets.
Also, all animals are more aggressive and territorial if not spayed or neutered, and it can lead to a lot of noise and fights, which can really upset neighbors and/or a landlord. Not to mention injured cats or local pets.
Feeding the animals without spaying or neutering them will help to ensure they're at least somewhat healthy, almost guaranteeing reproduction... so by definition you'd be creating more animals to feed.
It's really difficult, I know. Some people advocate doing what you can to help the animals, and that is admirable! But personally, I don't think helping them without preventing them from being able to reproduce is really helping. In my opinion, while I appreciate the tender heart that wants to help...at the same time, that admirable act helps create more homeless animals. Which almost defeats the purpose of trying to help....
If you want to help the animals, perhaps consider this.... if you're prepared to have them spayed and neutered, put out food to attract them. Trap them, have them spayed or neutered and vaccinated... and rerelease them. If it turns out there are only two cats (unlikely)... then that's all there is.
If more come... keep feeding and trapping until you stop seeing new cats. Then stop feeding them. This sounds very harsh ... but you will have achieved your goal of helping the cats, and your actions would have, perhaps, inconvenienced the neighbors or the landlord for a short time, but in the end you'll have helped the community by helping to prevent even more unwanted cats.
This might not be a popular opinion, but it is what I think.