Choosing an undergraduate research advisor I'm looking to complete a senior thesis (I would also want to do other research, but I doubt the viability of this) as an undergrad and I need help understanding how I would go about choosing the research advisor.
I am not really looking to do a masters/PhD as of right now, although this may change in a couple years. As of right now, I plan to go into the commercial market after college and would like to optimize for this.
Talking to some people in the workforce, I was told it would be very helpful to have a good thesis with an advisor that is well-known (high status) in the field. However, this seems to go against the prevailing sentiment on this site (1, 2). Why is it better to find a new prof rather than using a well-known prof?
Another problem is that undergrad research seems to be very infrequent (so there are maybe only 1 or 2 people I can ask about any specific prof a la this suggestion), so sampling bias is a large concern.
The third, and perhaps greatest concern, is I'm not sure what subfield I would like to work in (finishing all the lower division courses taught me almost nothing of actual use about the field, as there was a lot of hand-holding in those courses). Talking to some other students who went through this before me, I have heard that one should take a class with the professor before asking them to be one's research advisor (I thought this was BS and tried reaching out to profs, but got stonewalled - this seems to be systemic in my uni/dept). This only gives me a couple terms to take classes with different professors, trying to select classes where I get to both explore the field and get a good prof to research under. However, professors that tend to be more famous tend to teach more specialized classes where I don't get to explore as much. I am ok with pushing by GenEds out to take more classes in my major and explore right now, but am unclear on how to proceed beyond just choosing something that has an interesting title, hoping I'll like one of the 4 shots I have, and running with the best of the lot.
Any advice would be helpful.
Talking to some other students who went through this before me, I have heard that one should take a class with the professor before asking them to be one's research advisor (I thought this was BS and tried reaching out to profs, but got stonewalled - this seems to be systemic in my uni/dept).

Well, take it from a professor's point of view. They received an email from a student they don't know, who's only vaguely interested in their work. If you don't even know what subfield you're interested in, it's hard to write a convincing email explaining why you're interested in their work.
Mentoring an undergraduate is a time investment, not a time saver. So professors like to see motivated students who understand the problems they work on in their lab, which is part of the answer to your question below.

Why is it better to find a new prof rather than using a well-known prof?

Some people might say that older professors are busy as heck, and a newer professor might have more time to invest in a promising undergrad. Unfortunately, with COVID, finding a professor with time for an undergrad will be harder.
However, this isn't universal, and you should talk to previous students before assuming a professor is a good or bad mentor.
In summary, identify a few top professors, take their classes (as was suggested), and do well. That's at least a foot in the door to open the conversation.