- I have the brightness down to 30%
There's no standardised brightness scale, so 30% is meaningless. If you don't have a calibrator to measure it then it's just something you have to experiment with to find a comfortable level and if you're using it in a room lit by natural light you may well need to adjust it at different times of the day.
A high quality anti-reflective filter can also make a world of difference if your room lighting is such that they're a problem. Unfortunately I'm not aware of anyone that measures reflectivity of monitors as rtings does for TVs. Generally I'd expect it to be something that improves with higher priced displays.
That is part of the problem, displays tend to improve in several areas as you go for a more expensive model so without trying loads it's always difficult to tell whether an improvement is actually caused by what someone thinks it's caused by.
You could try turning off 'smooth edges on on-screen fonts' in advanced system settings>performance as I find that makes text unnecessarily blurry. Unfortunately some fonts these days rely on smoothing to look correct so it'll cause some text to look a little strange on a normal (non-HiDPI) monitor.