1. Product selection - I like photography and own a Nikon EDG 85 VR fieldscope, using the Nikon camera adapter to mount the fieldscope on camera as well. This purchase is for a coming Safari trip (Masai Mara, Kenya), where additional and portable binocular is desired. I read the reviews about Monarch 5 vs. 7, 8x vs 10x, Nikon vs. other brands, and settled down with Monarch 7 10x42. My friend wants me to bring him a Monarch 5 8x42 this trip, so I have a chance to compare. The higher magnification and wider FOV are the main factors of this pick;
2. Image quality - very good, clear image. The edge image quality is compromised, but generally not noticeable unless you intentionally looking at the edge. The wider FOV could be a factor. It you compare with other models with narrow FOV, Monarch 7 provides you the "extra" edge that do not exist on others. If you use the edge for "situation awareness", it fits the purpose. If the intention is to use it as camera lens, you may not like the edge quality. The EDG fieldscope I have produce much better edge quality, and it is not difficult to notice the differences (price is 8+ times higher though). The wide FOV gives the 10x M7 higher magnification at about the same FOV, comparing with the M5. (which is the reason I picked M7). In one occasion, I was looking at a large bird from not too far, the detail was great, the bird looks completely pop up from the background, but somehow the body of the bird looks flat. I will have to use it more to report later.
3. CA issue, that is widely discussed. There is a light CA when viewing against strong white sky, it won't be an issue looking at targets at ground level. For birding, it can be a concern. The Monarch 7 10x42 is WORSE than the Monarch 5 8x42 in this aspect. However, to get CA-free can be difficult. Even my EDG Fieldscope can sometime show minor CA in extreme case.
4. Build - made in China, very solid feel, even a little heavy! The control is about right to me, smooth and damped, not too loose, but easy enough for quick adjustment. The only problem is the poor lens cap design. The 42mm front cap is acceptable, but the operation is "rubberish", lack of the snappy feel; the other side is a lot worse, it doesn't fit at all and won't stay on. One has to use hand to hold it to stay. It does help to protect the lens when storing in the supplied pouch, I guess that is the purpose.
I think the M7 10x42 is a better choice for me, comparing the M5 8x42, for higher magnification with good FOV. But if CA is the top concern, you may think differently.