Whats the opinion on Nikon scopes
"Opinions are like [rectal cavities]..." But, since you asked:
I've always thought the ProStaff scopes were great bargains - I felt I got an awful lot for what I spent. I'm actually sorely tempted by an offering in the classifieds right now.
With the Buckmasters line, it was less so. I could abide them if I got a really good deal on a used one, but I'd not buy a new one.
I've never kept a Monarch, feeling that there was virtually no return for the money spent above a Buckmasters. New or used, I've not been impressed.
FWIW, I've never needed to interact with their CS people.
... and that's all I have to say about that...
FC