I've connected 27" Dell U2715H to MacBook pro 2012 and have a default resolution 2560x1440. It looks nice but the font size is waaaay too small, so I had to lose some of this niceness by scaling down to 2048x1152.
I wonder is this a usual thing people do? I know this kind of displays (27" 1440p) are popular as an external MacBook monitors. As far as I know, it's not possible to change the global font size. I can't imagine how people go along with this tiny text by default with 1440p.
A good question came up in comments about what do I consider a tiny font size, it's a good point, here's how it looks (full screen snapshots):
- Default 2560x1440:
- Scaled down 2048x1152:
My eyesight isn't perfect so I asked my colleague who wears glasses to take a look at it, he confirmed that it does look tiny.