I'm publishing a conference paper with 4 authors. I have the option to put myself as 2nd, 3rd, or 4th(last) author. Which is best?

My understanding is that 2nd indicates I did more of the actual work, but 4th/last indicates I was the "PI"/supervisor. I want this to look good on my CV when I apply for an academic position in the future.

Have you guys ever gotten into political issues over authorship?