Well if you don't need the extra power, it is best to stay clear of DEF regardless of what color. If your not going to use the power, no sense having a that extra equipment and hassle. That said, I recently had my first DEF issue on a 2018 CASE SV340. CASE had a program on the issue and replaced the DEF module for free. I have had 5 DEF machines and that is the first issue I have seen. If BC or Deere have issues with DEF, I have never heard about. Kubota and anyone that uses their motor is another story. Note that some under 75 horse machines still have a DPF even though they are not SCR (Kubota). Others don't have a DPF and are able to meet emissions without having a DPF (CNH and BC, perhaps others).
I am not sure what advantage one brand really has over the other when it comes to working on them (Tier 4 models). There is a lot going on in a small area, so working on them is never fun. They are all computer controlled so some guy with a laptop is required at times. The best advancement I have seen lately is the ability to have the dealer download codes from the machine remotely. Similar to what Onstar can do. They can also download upgrades from the factory remotely. That is a nice feature.
Some are EH controlled and some Pilot. Pilots have less electronics, but your also limited on what you can do with them. EH you can change patterns by pushing a button and dial the response to how you want it to respond, which you cant with pilots. My first EH machine in 2012 had some handle issues that were warrantied, other than that, I have never had issue with EH reliability.