My personal preference is for Arial Narrow - It allows you to fit more onto the page, without it looking too crowded.

However, any reasonably professional font will do - e.g. Calibri, Cambria, Arial, Verdana, Times New Roman. Don't pick any non-standard fonts - e.g. Comic Sans.

Hi, understand your struggle. Of course, the content of your CV is what the recruiters look at, but if your CV is well structured, looks light and easy to read from the smartphone screen (even by tired eyes) - that is undoubtedly beneficial.

I would suggest any light, simple, professional, not-proprietary font, designed to work well on screens (and not just on paper, like most of the serif typeface) - check out Open Sans, Geneva, Helvetica fonts family, and so forth. More familiar Arial and Calibri will work as well, but personally, I'm not a big fan of MS fonts :) just a matter of taste/habit.

Whichever font you chose, to ensure it looks correct on display across various platforms or paper (the interviewer may print your CV) - use PDF.

Hope that helps.