Like you said, I think there are pros and cons. My advisor is more well-established and I can see a lot of benefits from that. However, he definitely does not spend as much time with each of us as like someone with only one grad student would. Personally that doesn't bother me though because I still get what I need. I would agree that fit matters more, but also think about what you prefer - someone who might have more time to dedicate to you but less knowledge/resources, or someone who has more experience/connections, but will most likely spend less time on you. And of course that is just the average, I'm sure there are some new profs who still don't spend a lot of time, and some more established ones who do, but I think that's the norm. I would also consider being someone's first grad student kind of sucks because you don't have the advantage of older students to also mentor you, and increase your productivity by writing pubs w/ other students.