While Computer Vision Syndrome is real, be careful when researching how to "cure", ease, or prevent it. Much of what you read is pure marketing hogwash.
You should start by visiting an eye doctor to make sure you don't have a serious underlying condition. After that, getting prescribed a proper pair of computer glasses may be your best bet. One HUGE advantage of computer glasses is you can use them with different monitors.
You also need to define your needs and desires. For example, you didn't say what size monitor you want.
Also simple changes to your work environment may be all you need to improve any symptoms and prevent new issues. Start by cutting the glare from windows and overhead lights. Change the position of your monitor so it is slightly below your eye level. If your monitor stand has a height adjustment (a necessity for all my monitors), use that. Otherwise, you may have to put something under the monitor, or raise your chair.
Don't sit too close or too far away from the monitor. The ideal is typically about 20 to 28 inches away - but that can change depending on the size of the monitor and resolution.
Proper posture helps reduce stain on your neck, shoulders, back, wrists, elbows, hips, even knees.
Reducing brightness can help immensely, as can contrast.
And a big one - TAKE A BREAK!!! Stand up, walk and look around every 20 minutes for at least 20 seconds. Blink often. If necessary use eye moisturizing drops (plain drops - not the kind to get the red out).
As far as selecting a new monitor, again, you need to determine the size you want. Look for one where the stand has height adjustment too. Since desk heights tend to be fixed, and chair heights should be set base on your leg length so your feet sit flat on the floor, adjusting the height of the monitor is best done via a monitor stand that has height adjustment.
IPS panels tend to be easier on eyestrain.
Get a monitor with an anti-glare screen instead of glossy.
Anti-flicker and/or high refresh rates help reduce eyestrain too.
Many monitors have preset options to reduce blue light emissions. These may be actual filters, or simple menu settings. A new marketing gimmick is to call those common simple menu settings some catchy eye protecting technology - then charge you extra for it. A rose by any other name is still a rose.
