Depends. But usually being first author counts for more in most fields. However, e.g. in particle physics papers with hundreds of authors are common, alphabetically sorted. Sucks to be Z. Zymmer, nice to be A. Aaronson. People from the field of course know about this. Sometimes they might even act accordingly. But politicians and administrators far too often don't.

And then there is bibliometrics, the art of lying with publication statistics. Everything humans get wrong is even worse there. A. Aaronson is different from Al. Aaronson, right? No paper has more than 3 authors, right? Journals always count for something, conferences don't, right? etc.