I don't really have a rec, it depends on your budget and preference, although I personally went with Comix Well Spring since they weren't too expensive and you can have customized book/page dimensions. The downside to them is they only print in bulks of 25 books, so the cost after shipping can rage around $400 - $600 depending on paper quality, page count and custom cosmetic features. I know that some folks from the collective I'm apart of use Ingram, which gives the option to print books on demand, although they're a little more pricey per book and dimensions aren't as customizable. I've thought about trying them out myself since it wouldn't be a painful investment, but I don't have the time to edit the dimensions of my pages at the moment. (Editing 192 pages can be a lot when you're strapped from time and energy. Lol)
If you're willing to make the time I'd suggest going over to Spider Forest and either ask around on their public Discord server or in a forum thread. The members have a lot of experience with self-publishing, and can give you amazing feedback based on those experiences. If you do check them out try to engage a bit, they're all really nice people who appreciate conversation.
