I see you already have alot of answers, but I taught preschool and head start for many years and wanted to share a couple of thoughts with you.
First of all my heart goes out to you, your partner, and your little one. I admire you for wanting to take the time to make the very best decision for him and for you.
Preschool is good for a lot of things. Surprisingly he can get several of those at the playcare. The skills learned at a preschool that are most helpful for later learning are social skills, listening skills, and negotiating skills, how to start and stop one activity and move to another, communication skills. All of these are skills that can be learned in a home playcare as well. A child can be super duper smart, ahead of the game even, but if he doesn't posess these skills he has a more difficult time in kindergarten than if he came in having never learned a thing about numbers, letters, colors and the like.
Preschool fosters curiosity and a desire to learn new things. The beautiful thing is that you can do that, too. With just thirty minutes a day, you can introduce him to ideas and concepts that will spark his interest and make him curious to learn more. You don't have to be a seasoned childcare professional. There is a pretty good chance that he might actually learn better with you right now, in a comfortable and not overstimulating environment. You can teach him numbers by letting you help cook things and dealing with the measurements. You can teach him colors using egg dye, jello, fruit gummies, and a million other things. You introduce language and it's uses best by reading to him, getting repetitive books that are easy for him to memorize and letting him "read" them to you.
I would stick to the playcare situation and just pick up the slack in the learning department, if I were you. And if you want any ideas, feel free to email me and I will send you some that are easy and cheap, if not free.
Hope this is helpful,