I found these guys on Etsy (where they have great reviews) and then tracked down their website — can anyone vouch for their tile quality?
I have found Cemento in my research too and would put their quality in line with Zia or Riad for Zellige (based on samples). I have seen a lot of creators work with them recently, but cannot personally vouch for their quality for a finished product. Cemento seems to be slightly more expensive but has shorter lead times.
If you are going for Zellige, I was most impressed with the quality of Riad. @danielaaraya has used Riad a few times too I believe.
Yes I love Riad! Not exactly an answer to your question @hilahstahl because I also haven’t used Cemento, but I loved the quality of Riad and they were also super responsive/helpful throughout the process. It seems like Cemento has colors similar to Riad too. I would get some samples and see what you lean towards. Loving the blue and yellow options I see on their site 
ok i can confirm after getting the samples that Cemento is both high quality and also has a nice “polished” zellige meaning it’s rough and imperfect like you’d want it to be but not so much so that it will be really tough to install or make look somewhat uniform. i can send pics or write this up more if people are interested 
Ooooh yes please share! I’m so curious!!