Sony or Fujica?

Which company is producing the more advanced cameras?

Do you mean Fujifilm?

-And why do you ask?

The "best" camera depends on your needs and, of course, budget.

Every camera has a list of features and attributes. It's up to you to make that list and and prioritize. If you get into sticky situations where you might need to break heads, I would rank a Leica SL near the top of the list, followed by any of the Nikon Z cameras. That was no joke in the 60's, or even last summer.

As suggested, "more advanced" is a very shaky and uncertain concept even if it were* limited to something like "which is the most advanced sensor" or some such.

Personally, I suspect, but am by no means up on the 'latest thing' from either of these manufacturers, that the only possible answer is

"in what way, more advanced".

Both have, in the recent past (for me, the last 10 or 15 years), tried some alternatives to the more-or-less 'standard' capabilities/designs of Nikon and Canon.

Despite a following for these alternatives, most of us have pretty well settled down to the big two.

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*WERE - non-native speakers of English will note the rare use of the subjunctive mood (or case, as it used to be called) ;)