If the Tier 4 components are of particular concern to you it is my opinion Deere or Kubota are the best bet. Together they have 80% of the CUT market in the US. So they should have spent the most R&D on these US requirements. While it's no sure things I'd put my money on there systems having the fewest problems.
I think Mahindra, Massy, and especially Kioti make excellent equipment (and maybe better than Deere) they just don't have the same US directed resources.