Easy one - either the Deere 825i or a Ranger 800 XP. If on a budget, find a Rhino 660 or 700. Kubota is useless except for golf course work. I've owned all these machines, as well as a RZR 900 XP, and the one I drive the most (by far) is the Gator. It's perfect for work, clutched very well...
Here's my rating of each, regardless of age or size:
1. KTM 505 - wide stance, race ready, holy ch!t power, awesome deals on em
2. Banshee - No need to explain, and CHEAP
3. 250R - legendary (but expensive), considered a collector at this point
4. YZF450 - regardless of year or configuration...