Eh... I'll try. I don't want to name any names or show spite.
One company, the process was a mess. The recruiter I worked with was fired in the process, which took a few days to sort out. It had many rounds of interviews, each expecting me to purchase material to study. One interview was absurdly bad, one of those 'well, that's not what it says on my paper' types. One interview the interviewer seemed almost condescending, asking questions with no possible one right answer.
Another company was much better in most regards, except when it came time for reimbursement. It was a bit 50/50 on whose fault it was, but it amounted to me being on the hook for a few hundred dollars. Not the end of the world, but I was sent a short rather cold message that made me feel like they thought I was trying to cheat them. I was trying to inquire about meeting me halfway, or what I could have done differently to avoid this, and never received a reply. As soon as I removed the flagged charges, it was paid and closed with no further communication. For a company who brags about perks and whatnot, the way they handled that turned me off. It was one of those 'notice how people treat people from who they have nothing to gain' moments. To add insult to injury, another group asked if I'd like to come back out. I replied rather short to that, which in retrospect I feel a little bad about.
That said, it is true I didn't work for those companies. But to me, a recruiter or interview process is a first impression. It's their face to me.
If I'm off base, though, I'd love to hear tales from others.
Edit to add - I will name one company that I really liked their interview...a company in Texas called Meteora. They were using tech way ahead of its time when I interviewed. They never asked me filter questions, or treated me like 'another applicant.' I talked to a competent engineer who explained what they did, what was needed, and their tech stack. I was honest in having no experience with this stack, and they were honest in telling me I wouldn't be a good fit. I wish all interviews were as simple.