I just spent a few days researching this for a new work project. It's a toss-up. There's many dozens of PCBA companies in the US. Most are much more expensive

I just spent a few days researching this for a new work project. It's a toss-up. There's many dozens of PCBA companies in the US. Most are much more expensive than JLCPCB. To make matters worse the user interfaces on the majority of them are horrible. No thanks, I don't want to count the number of SMT pads for you because you can't hire a few software developers. There are a few PCBA vendors I found that have good user interfaces: macrofab.com, circuithubs.com, tempoautomation.com. Likely there are more but circuithubs.com has been my favorite so far on a good UI and reasonable price. They have a github inspired flow that I like. After searching, I still believe there's an unmet market in the US for a JLCPCB style PCBA vendor that has a in-house SMT parts library and can therefore offer a price that's 1/2 to 2/3 cheaper than other American PCBA vendors. If OSHPark offered it for example (select parts library they can place cheaply) they'd become my goto.