One. Portable and stealthy. Rarely hunt the same stand twice and rarely enter an area until I am ready to hunt it. In the earlier days, and as I watched guys hunt, it became quite apparent that mature deer encounters or harvests were typically first time on stand. I have come to believe strongly that going in and out educates deer. I like to wait until the right time and wind, slip in and hunt.
With modern equipment, I have 20# on my back (stand and sticks) and I can get up a tree in 7-8 minutes. I can go to a new spot, change in the middle of day, even scout and hunt the moment I find what I am looking for.
Dan