Both Shiels and Finch do extensive testing to see if they can measure the performance differences between top brands like the Titleist Pro V1, other top-tier competitors, as well as market-trailing brands. Some examples of their testing videos are below:
Shiels prefers to compare a brand's offerings primarily against each other in his reviews. He uses both on-course and closed data to find performance and feel differences between various balls on offer from a single manufacturer. However, by comparing the testing results across his various reviews, it isn't difficult to determine the relative performance of the products to each other.
Finch takes a different approach to his reviews. His format is a direct head-to-head comparison of what he calls "guerrilla" brands put up against the market leader, again, the Titleist Pro V1. To date, he has focused exclusively on using closed data and feel to compare the performance of these upstart brands against the Titleist but is promising future videos that will include on-course results as well.
Your Mileage May Vary
What is important to remember as you watch, and I do encourage you to do so, is that both Shiels and Finch are PGA teaching professionals with games that are far better than the average golfer. To their credit, Shiels and Finch do concede that their results may differ from ours. Their statistics and opinions are really meant as a starting point to help us begin our own testing to see which ball performs best with our own game.
There are other places to find similar reviews online of course, but I find the presentation style and quality of the reviews provided on these two channels to be superior and well worth your attention. Both Shiels and Finch work hard to provide unbiased data to help the average golfer learn more about how each golf ball performs beyond the usual hype on the box. If you're in the market for a new golf ball, and who honestly isn't, you can't do better than starting your search with the reviews put out by these two gentlemen.