JLCPCB does tons of sponsored segments on YT. I see them more than Pcbway.

JLC advertise constantly, just look at the eevblog forums.

  > JLCPCB

How are they?

I've only used them once for my first (and so far only) PCB, so as a complete amateur, it was great. They rejected my first design which had an obvious flaw, and my second design was in my hands a little over a week after I uploaded it. I paid 2.60EUR for 5 (tiny) PCBs and 7.50EUR for the shipping. They even placed and soldered components for me.

That's very reasonable, especially if those were SMT components.