The monitors have built in, non-adjustable stands, so they sit another 6 inches above the desk so the bottom bezel of the monitor is pretty much at eye level. This causes neck strain because I'm looking up all day.
This looks like an OSHA violation. If I'm reading [the OSHA documentation] right, the top bezel should be at eye level, not the bottom one.
I'm resigning for ergonomic reasons.
No, you're not. You're leaving because your employer refuses to make reasonable accommodations for you.
Going by you explanation, you didn't ask for anything unreasonable, just for a comfortable working position, to prevent strain and pain. Even it isn't an OSHA violation, your employer has shown a stubborn unwillingness to accommodate you.
There is a balance to be found between pampering and tormenting one's employees. Your current employer seems to be leaning towards the latter.