It sounds like you are comparing binoculars.
These are my thoughts:
1. The first thing to realize is that if everybody saw things identically, we would have a consensus on what is better than what in optics. This consensus doesn't exist, so there is some individual preference in evaluating optics. Some people prefer contrast, some resolution, some brightness, some other optical properties. Each optical design is different on how it accounts for each.
2. Sample variation is something to remember. Within every particular model, there are "cherry" specimens and "lemon" specimens. Above all else, I think this is where most disagreements can be traced back to. When you decide on a particular optic to buy, I would do my best to check out a few samples to find a "cherry."
3. In optics, some things are independant of opinion: These are things like distortion (in the proper optics use of the word), aberration control (chromatic and spherical aberration particularly), field curvature, and field of view. A good review usually identifies these qualities as well as the reviewers general opinions.
The Viper HDs are pretty competitive, IMO, although the FOV isn't really wide. For their price range, I have a hard time finding something better, especially considering the warranty. Make sure to find a good unit.
The Conquest HD is a quality, well-built binocular, with very good center-field performance, but struggles with CA at the edge. Meopta has a similar binocular called the MeoPRO HD which performs similarly with a wider FOV and softer edge.
The Razor HD also a quality binocular that has similar centerfield performance which degrades towards the edge, with some field curvature affecting edge performance.
The Meopta Meostar HD is my reference binocular for 10X42s with no real optical or build weaknesses. I replaced my previous reference standard Swarovski SLC neus with this model. I have also used a number of copies of this design and find it consistently excellent. It is the only mid-priced binocular I have tested that I would put on the same shelf as the flagship binoculars from Leica, Zeiss, and Swarovski. That is my opinion, and I don't mean to say that it is exactly equal to or superior to those models, but it certainly at least compares.
I have just started evalutating the Mavens, so it is too early to say on them.
Hope that helps.
