A lot of it depends on viewing distance. If you are sitting far away, those larger pixels are less of an issue.
Back to your original question, I would take resolution over going beyond 60Hz refresh. I’m on a 27" LG monitor, with a 4k60 IPS panel. The game fluidity is great when running at 60fps (albeit only if I’m at cruise altitude). I would say either get a 4k60 IPS monitor for under budget and put the extra money into a better graphics card, or go with a larger screen size if it fits your current budget.
If I could do it again and money wasn’t an option, I would’ve went with at least a 32" monitor because viewing the gauges in a glass cockpit from the default camera position is a bit hard on my eyes. 4k resolution and 60fps is plenty for me in terms of performance. At the time, I actually thought 27" would’ve been on the large size in my space.