The Monarchs are a better scope period with better glass and coatings and will be brighter than a buckmaster. Usually you divide objective size by zoom setting and that gives you exit pupil size and that would give you relative brightness. But the Monarch has better glass so a straight comparison like that is not valid. If you can afford it get the monarch. If you cannot afford a Monarch get a Team Primos 3-9x40 as it is a Monarch UCC with a BDC reticle and a different name to trick you into not thinking it is a Monarch for $220, but that is what it is.
Oh and to the original topic side focus is worth it if you are a long range target shooter and need a side focus to quickly adjust for parallax. Otherwise the rear focus does the same thing. I hunt and have never touched the focus ring