I've always been happy with my Lincoln welders. I had a small issue with the V350-Pro when I first got it. In my area there are only two welding repair shops. I've been going to one of them for years, they take very good care of me. They handle Lincoln and Miller for me!
I would really like to get my hands on a Miller XMT-350 to compare it to my V-350-Pro.
My Miller Dynasty 300 made a Tig weldor out of me! Miller vs Lincoln same thing as Ford vs Chevy vs Dodge. I think it boils down to the model that fills your needs.
If anything I lean towards Lincoln for engine drives, and I should know. In 1983 I paid $9,378.00 for this one.