For new, you might consider a Millenium. Been out for a couple years now. They use Kubota motors and Yanmar (aka JD) drivetrains is my understanding.
Penrose Manufacturing in Penrose CO, had the best price on a package I have ever seen. Brand new 43hp diesel 4x4, hydrostatic transmission, every 3pt attachment known to man (auger, blade, box scraper, mower, and a backhoe, plus others I am probably forgetting), and a loader. All the attachments were Great Bend, Kelly, or Land Pride. $24K. Beautiful, high-quality tractor, kind of maroon in color.
Used? I'm partial to the big green ones, I have a mid-1970's 60hp 2030 diesel. I thought it might be too big at first, but now I am convinced size does matter. Moving dirt and 800lb squares, and 1300lb rounds with the loader off a stack, would not be possible with a smaller tractor. I would buy something smaller if I didn't have all the leveling work and and baling work, but the size so far has not caused any issue with maneuvering or accessibility.
later, jon.