We have stayed at Fairfield once and Hojo many times. Our stay at the Fairfield was fine. The parking lot was a tight squeeze, but we did not have trouble getting parking. I do hear that the charge for parking these days, which they did not during our visit several years ago. The room was clean and spacious enough for our family of 2 adults and 2 children. I would recommend getting a Disney side room rather than a highway side room. I would make a similar type recommendation for Hojo too, don't stay on the highway side of building 1 there unless you are willing to make the noise trade-off for a kids suite, not worth it for a regular type room.
The reason we keep going back to Hojo is ultimately price. In our case, since we have APs, we can get 20% off whatever the going rate at Hojo is. I rarely find a place that is within walking distance, that I don't have to pre-pay, and that comes out cheaper for the whole stay. That being said, if Fairfield came out cheaper, I don't see any reason not to consider it. The walk is slightly less, you're still next to Mimi's, and you have the basic amenities.
BTW, Hojo has a separate pool as well as the water play area. My 9 and 11 year old boys enjoy both.