Specialty tractors tend to come in either narrow and lower stance or wide and lower stance. There companies like NH that offer some of these specialty tractors, however I don't know what they offer in the US.
Isodiametric tractors, like Ferrari, Antonio Carro and others, are great to use on hills, after all those were made for hills and not even comparable with Ventrac or Steiner. Antonio Carraro is a couple steps above Ferrari/BCS/Pasquali (all made by BCS) in quality and finish but as you may imagine, in price as well.
There are two dealers that I've read nothing but absolutely great things about them. One is in PA and the other is in Florida. I'm sure there is plenty more, but I'm not aware of those.
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@Tunin from Bosnia and Herzegovina dealt with the AutrUSA dealer and had a very good experience.