best monitor calibrator?

Good:

Datacolor SpyderPro4 Display calibration system or X-Rite Colormunki display. These will give you good calibration for about $170 USD.

Better:

Datacolor SpyderStudio or X-Rite Colormunki Calibration kit will give you very good display profiling and will let you make printer profiles as well for about $450.

Best (arguably):

BasICColor Discus 990 Euros (about $1,300) includes BasICColor Display software. BasICColor is very good software and the Discus is a very accurate colorimeter with several features such as constant temperature monitoring of the sensor (to correct for hotter/colder sensor giving slightly different readings). For most people this is overkill. The BasICColor software also works well with other colorimeters and spectrophotometers which can be a cheaper option.

Insanity:

PR-655/PR-670 along with some higher end software this gets into the territory of "if you need to ask the price, you can't afford it" around the price of a new car.

If you do not have the lighting in your room carefully controled (ie.: there are no windows, when you turn the lights out it's pitch black, you have D50 or D65 calibrated lighitng, you've made sure the illumination from the lighting is very uniform across the room, all the walls are painted a completely neutral color, and more) and you probably won't notice much improvement going beyond the Spyder or Colormunki systems.

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\~K