Good evening Garrett.
Iíll toss in my two cents. For reference, in my off time, I lead birding tours for donors for conservation groups. So, I have the opportunity to see lots of binoculars and spotting scopes and put them to some pretty good tests.
In spotting scopes, size does matter both in terms of performance and weight. In terms of performance only, the 77mm and 82mm are the best. The majority of birders use either Leica or Swarovski, with Kowa making a comeback recently. The Swaro has the better zoom eyepiece at maximum magnification of 60x. The Leica has the better focusing system and in my opinion better color fidelity. Also, in my opinion, the Leica has the better ability to see through excessive reflected light conditions such as hot, humid air or snow and water. For the no holds barred category, stick with either Leica or Swaro. Some also favor Kowa in the top tier, but personally I think that while they are good, they still have not come up the level of Leica or Swaro.
If you plan on carrying one hunting, weight really does matter. The 60-62mm class are almost as good as the full size scopes, but much more compact, lighter, and easier to carry. Also, the 60-62mm are a bit less expensive. Again, and this is just me, I would recommend sticking to Leica and Swaro. Kowa is almost as good. Spend the extra dollars for the flourite lens if you can afford it. If you plan on sticking to the range, go with the full size scope, they do outperform the 62mm at long distance. If you really plan on taking one much in the field, go to the 62mm.
Personally, I prefer the Leica over the Swaro, but it really is a personal preference as both as superb. I have an old post on performance factors which you might find helpful. Look through several before you buy. With either, go with the 20-60x zoom which is more useful in field use and only gives up a slight bit to a fixed power with respect to resolution. Among the fixed eyepieces, the Leica 33x wide angle has wonderful resolution.
One tip fwiw, always leave the lens cap on the "big" end unless you are using the scope. You should rarely to never have to clean it. My current scope, a Leica 77mm, is over ten years old and I have only had to clean the lens once. With the top end scopes, the extra price is mostly for the lens and especially lens coating, which is sensitive to excessive cleaning especially dust removal. Use a "lens pen" or similar brush to lightly brush off the dust. The eyepiece end will need much more cleaning but is not nearly as critical to the overall performance and so is less sensitive to cleaning. If you can afford it, go for the top end the first time and don't look back. A great scope, and great binoculars, are joys to use.
Here is an example of the type of performance demands I have in searching for birds with a scope.
Good luck with your choice.