What are you comparing the font rendering to? Linux/Windows?
That's one of the things that pushed me to Mac from Linux: fonts finally looked nice. (This was around 2010.) I tried everything I could to get Linux to render decently but eventually gave up. I recognize that this is so much down to personal taste. If you prefer Windows-style ClearType to Mac's rendering, Mac (especially on a non-Retina screen) will look awful. If you like Mac's rendering, Windows tends to look awful at any resolution.
That's one of the things that pushed me to Mac from Linux: fonts finally looked nice. (This was around 2010.) I tried everything I could to get Linux to render decently but eventually gave up. I recognize that this is so much down to personal taste. If you prefer Windows-style ClearType to Mac's rendering, Mac (especially on a non-Retina screen) will look awful. If you like Mac's rendering, Windows tends to look awful at any resolution.