Print quality is decent. I have some quibbles about quality on the saddle stitched books, but it's possibly improved in last 5 years and presumably you're thinking about perfect binding, which differs a bit in terms of print process. I would say that if you're wanting to self-publish in limited run at lowest upfront cost, they are fine and generally very easy for beginners to navigate (esp compared to Lightning Source IME).
One thing I'll add that isn't very clear upfront is that the free ISBN Lulu provides when you set up a project is registered through Lulu, meaning they are listed as the publisher, not you. For many projects, this may be no big deal, but it can create issues as far as how the book is listed or if you plan to republish, particularly through another printer/POD. We decided to do a second edition of a book initially published through Lulu via another POD and this detail became a bit of a hassle. If we had known, we would've paid for our own ISBN initially. It may not be a problem with your project or a lot of small one-off projects, but it might be good to know.
Definitely something I would recommend! You retain ownership of the work itself with Lulu's ISBN, it's more the publishing rights that will become an issue, like if you were to decide to print through another vendor or republish portions of the work elsewhere. It also affects how the book is listed, i.e. while you will be listed as author, Lulu is the publisher. If you wanted to publish several books under a press name (which we were trying to do), this can be especially problematic.
Anyway, sounds like you're doing your research, which is good. Only other recommendation I can make is go in with a marketing plan, even if your goal is as basic as aiming to sell 50-100 copies. Like, have an audience in mind and venues you can market to, along w/any promotional costs as necessary. Seek out reviewers and blogs, yada yada.
Ingram owns both IngramSpark and Lightning Source, so it looks basically like printing through LS. Main difference is that Spark is designed for authors vs publishers, meaning it's more user friendly for beginners and easier to get started. Dashboard shots look similar to Lulu. They were just getting started around the time I stopped designing for book projects, so I had actually not heard of them until just now. IDK how they price compared to LS, but could be a better deal than Lulu. LS has better stock and finish options IIRC, but for a standard glossy cover w/text this doesn't matter as much.
Yeah, I know I researched Createspace nearly 10 years ago when I got started designing book projects, but we didn't like them as much. The main advantage is it's very easy to get started selling through Amazon.
I might turn the manuscript into a graphic novel instead. (I'm a very indecisive person) So I guess I'll be looking into their abilities for that as well. My story is very visual so it might be a better option than page long descriptions of how a building looks.
I've been using LuLu to publish the hardcover editions of my novels since 2005. Never had any problems with them. Used to use them for my paperback editions and ebook too, but in 2010 Amazon made it easy to publish ebooks on Kindle without having to create a .mobie file anymore, and as of a year ago we can now publish paperbacks through Kindle as well, so now I only do my hardcover editions through LuLu.
I've bought copies of all my own books so I could see the quality myself, and the quality is exceptional. No difference between them and what you find on bookstore shelves. Very high quality work. I highly recommend them.
Hey! Brighter-Future used the website to print our art book. We used the print-on-demand service, which is a pretty great option for authors who don't want to spend thousands of dollars upfront. The printing quality is great (although obviously we printed an an art book so we used higher quality paper than you'd want for a novel). If you'd like to see their quality, you could try buying a book from there to take a look as well! I personally found it a very good website for what we were doing, but we had all of our content ready and didn't need to interact much with the interface and such for say, cover design.
Hope this helps, and let me know if you've got any more questions about the process!