You'll love G-Sync + Higher Hz...I'd personally recommend a 27" 144p panel, it;s really not that large and you'll quickly love it's size and pixel density. I purchased the Dell2716DG a few months back...
27" is too big for my desk and I cant be sitting so close to a monitor that big.
That's too much resolution for 24", so they don't make such screens. If they did, you would have to use Windows high DPI settings because everything would be too small to read/see, which is always inadvisable.
Don't worry about sitting too close to a larger desk monitor with higher resolutions. Mine is a 34" Ultrawide curved Predator G-sync and it's perfectly comfortable on the eyes. I previously went from 24" to 27" and that, too, was very comfortable on the eyes.