first, i always try to choose the hi hats, which will be in right contrast to kick and other elements in the track. when i'm eqing i do whatever sounds good and help them to fit well in the track. mostly rolling off the bottom and then shape the sounds as i need.
i put all the hi hat channels into a group and then compress the group little bit and also compress each channel with hats separately when needed.
then i use reverbs, which ii have got in send busses,. mostly it's some early reflection, and then some more ambience verb, but not too long and wet.
some hats sounds good when they are mono and some works nicely in the wider stereo field with more amount of verb and delays,, probably tambs and stuff like that. when i need some more crunchy hi hats i use some distortion,cruncher,or something like that.