I was at a red light. I pull up to the light and another Wrangler is there. He waves, I wave at which time a third Wrangler pulls up and now we are all waving at each other at which point a fourth Wrangler pulls up and it begins again. I was so glad for the light to finally change, jeeeez.
But, if it is a JK Unlimited, unless they wave first, I do not wave at them. If they waved, I wave back. JKU people often, but not entirely, are not traditional Wrangler/CJ people. If you are in a JKU, you might need to initiate the wave, at which point, most will gladly wave.