I think most of us on this forum are on a budget. Your accessories will probably reflect what you can afford.
Most common (maybe not in order)
Winch (first on my list)
Tires to match your style of riding
Roof protects us from the hot sun, you might want one for rain and snow
Windshield for rain and snow and cold wind (understand that with the windshield comes dust)
Power steering is popular
Lights (lots of lights)
Mirror to glance behind you
Some means to carry your stuff (Honda has the least amount of storage)
Radio
Spare tire
Better shocks (My favorite so far)
Bumpers (beefy bumpers)
In cab heat (not many found in Louisiana)
Full cab enclosure
Stick stoppers
Oscillating Homoginator
Skid Pan
Curb Feelers
Fuzzy Dice