The one font that I despise the most is Arial. It's used everywhere in professional documents, but it doesn't have the professional look and feel of Helvetica, which Arial is supposedly a knock-off of (there's so many differences between the two fonts that I can't explain them all, but some of them are obvious if you look closely enough.)
Whenever I use a sans-serif font in certain important documents, I prefer to go with Helvetica, if it's available to me.

I'm also not too crazy about Courier New, as far as monospace fonts go. It's so doggone thin compared to the real Courier as used by typewriters. I prefer Prestige Elite when it comes to typewriter-style monospace fonts, even though that particular font seems to have fallen out of use many years ago. (Both Courier and Prestige were introduced decades ago for use with IBM typewriters.)