All three are very potent strains often used for medical mj use. I'm not sure if you could say either is best, more a matter of personal taste. The big differnce between Jack Herer and Hawaiian Haze is that the Jack Herer is(supposedly) an indica with a heavy body high and the Hawaiian is a sativa with an up high.

I've got some Jack Herer right now and it's a serioulsy debilitating smoke. Too much of this and you better find a nice comfy couch to lie down on and enter a vegetative state for a few hours. I like it as an end of the day smoke before going to bed.

I've never smoked pepper jack but I've heard it's pretty nice.

If you have a choice between these I'd say pick at least two and get some of each.