In the Nikon line....
I own both ....5 buckmasters of various power ranges, and 3 Monarchs of various ranges. They all are the new side focus models except for two..... and those two are 16 years old.

If I had to be honest, I would get the buckmasters and get as much scope ( power or Obj. mm ) as I could for my money. I just have not seen THAT big of a difference betweer the models. I love the Nikon line, and that is about all I will buy anymore. The Buckmasters is close enough to the Monarch that most people will not notice any difference, and that is only in the very first few minutes of shooting light , and the very last few minutes of shooting light. And facts are that most deer are killed after first light or before last light, so that is not a big difference maker.

I think you would be pleased with the buckmaster. At least check it out before you decide.

BTW ... go with 3 - 9 x 40 minimum. Depending on how you shoot, something on the idea of a 4-12 or so is not out of the question. I used my ML with a Nikon Buckmasters 4.5 -14x40 two take two 8 pt.'s this year.