This is similar to your other question in that you're asking something that is very subjective. How much brightness you need depends on your environment. Do you almost always game at night, or with thick curtains closed. Do you game in a basement or a room with tiny windows which never get direct sunlight? If any of those are true you do NOT need bright monitor at all and in fact it would be much better for your comfort and long-term vision to turn your brightness down to 150 or lower. If your gaming at night with just a dimmed light on, even 100 cd/m2 is actually more than adequate and saves your eyes.
If, however, you're likely to be gaming with direct sunlight on your monitor, then you want the brightest monitor you can get... and even then you'd be better investing in some curtains or blinds or something.
The sun is incredibly bring compared to any (normal commercial or residential) lighting. So sunlight is the only thing that will demand really high brightness. Even closed blinds in front a big window in direct sunlight will fill most rooms which far more light than any electric bulbs will.
Decide what brightness you need for your environment and then shop accordingly. Most monitors have the best colour and contrast somewhere around the middle of their brightness, although certain (usually more expensive monitors) remain solid across the brightness range. Once you've determined what you need, then you look at reviews which test the brightness you want and you're good to make an informed decision.