I would also lean very heavily towards the Pioneer 700 for farm work.
The P1000 is a 60 trail/40 work vehicle in my mind. The P700 is the inverse a 40 trail/60 work vehicle. It doesn't have as nice of a suspension or as much power or as much top speed but it has a very mature transmission system (Honda Rincon) that is nearly impervious to user induced damage. You can go as slow as you want and never have to worry about it. There are lots of videos out there and comments around of how people are using their P700 for trail riding and going pretty much anywhere a Pioneer 1000 goes but you won't see many "my P700 sucks" because the clutch is burned up/ingested water driving down the trail/drive mode out of adjustment/etc that you see with the P1000.
I would definitely look at getting the Deluxe model that has the manual shifting option. That is a really useful function. I used it all the time on my old Honda Rincon. It is very useful to keep it from shifting at inappropriate times plus you get power steering as well. That is really useful if you hit a rut/gully/etc and it won't break your thumb/wrist by jerking the wheel.
The P700 doesn't have turf mode however, if that is something that you think you might need, I would probably look at a different brand. You also might want to look at a different model if you are in a higher altitude area as the Pioneer 700 doesn't have a large amount of surplus HP and it doesn't have a low range so it might have some problems when the air gets thinner.
The Kawi Mule Pro is quiet, beefy, powerful torque and has a turf mode, a very large metal bed and is standard with a 3 year warranty but it is about a foot and a half longer than the P700/P1000, heavier and doesn't have a locking front Diff. Of course, neither do most people's 4WD/AWD vehicles that they drive everyday either.
However, it does have a 3 cylinder automobile engine that is very well respected throughout the world for use in small car and is darn near bullet proof and it has a massive set of running gear.
My local dealer sells Can Am/Arctic Cat/Kawasaki/Polaris. The Mule Pro FXT is his number one seller followed by the Can Am Defender. Farmers around the area love the Mule Pro. We have flat to rolling hilly land.
Personally, I wouldn't get a Polaris. I have been around too many with too many problems.