3' is the absolute minimum, but for someone to pass behind you while you are standing at one, anywhere from 3'-5' is best. I always design in 5', and take it to a minimum of 42" if there is not enough room.

I agree that 42" would be good.

You also want to make sure you have enough room to move your appliances in and out, and with the huge fridges, the more room you have the better.

Another reason for leaving ample room is in case you're ever in a wheelchair or need to call 911, and they need to maneuver a gurney around that area.