In no particular order, but equipment I recognise I use frequently. Probably missing a bunch of other stuff.

  - Cab heating (keep warm when cold)
  - engine block heater (start vehicle below -25C)
  - windscreen wipers (clear snow/dust from windows)
  - demister/deicer (quickly clear fog/ice from windows)
  - air suspension seats (stop spine popping out of butt)
  - Cab air-conditioning (keep cool when hot)
  - cab air filtration (reduce chance of nasty lung conditions / death)
  - power-steering (be able to turn without arms falling off)
  - wet-braking (nice to have breaks when you need them)
  - a handbrake that works (safely keep vehicle running while unmanned)
  - multiple lockable diffs (you WILL get stuck in mud without these)
  - multiple range gearing (go super slow without stalling and also go fast enough on highway)
  - quick-reverse (switch from forwards to backwards quickly)
  - reversing/positioning cameras (so you dont hit stuff you dont want to hit, and do hit stuff you want to hit)
  - bluetooth entertainment system (podcasts, audiobooks)
  - soundproofing (soooo loud otherwise)
  - winch (get unstuck without waiting for help)
  - CTIS (save about 20 mins a day solely adjusting tyre pressure from field/road)

Im sure you can do without a bunch of that, but you will just be miserable for much of the year (or you dont actually spend much time operating).

I guess you could add safety equipment to that as well. Rollcage, multi-point harness, etc. Theres also the obvious stuff that you just need to do the job - tow hitches, 3-pt mounts, PTOs, etc.