I've always found that the "top at eye level" to be not so helpful.
I saw a pricey chiro in London who gave me advice i swear by - eye level should be at the 50-75% mark of the monitor.
In the same way that we don't tilt our heads to look at the top of a painting we're viewing, keeping the eye level roughly in the middle (i prefer on the high end at about 65% monitor heigh) keeps me sane.
I just requisition blocks of (sealed) printer paper from the supply cabinet to get my monitor to the right height.
I don't think your weight/seatheigh/deskheigh play a part in the monitor height. On the other hand, i've read that
for seating you should have a slightly greater than 90 (~>90) degree angle between quads and back, and ~>90 degree angle for forearm to bicep. Also, a ~>90 degree angle for calves to quads.
Feet are meant to be flat on the floor in this scenario, not dangling.
Obviously then you could presumably get a "magic number" that would be the height of a given monitor from the floor for a person, but you'd need to know the lengths of varying body parts.
If your neck is bugging you, have a look at you seat too - a seat can cause issues (maybe you sink into it? Maybe it is slanted to one side? etc) that can cascade up the body to seemingly unrelated body parts (eg neck).