If you are left handed there are better scopes that dont have the eye piece offset to the side.
With a rotating Band on the 821M or the 82SV there is no left hand or right hand concerns with an angled eyepiece. You definitely want the angled eyepiece and rotating band on any spotting scope for shooting purposes.
I'm just a Service Rifle shooter but half of our 80 round matches are fired from prone.
Two rapid Prone strings of 10 from 300 yards and then 20 record shots slow prone from 600 yards.
Chad, As you likely already know;
Especially for prone just as important is a scope stand head that gets the scope out away from the stand and closer to the shooter.
You don't want to have to break your prone position to monitor mirage ( primary purpose of a spotting scope ) between breaking shots.
The Polecat is an awesome stand and head that does just that and makes it very easy to set up the scope.
https://www.creedmoorsports.com/product/1357/Scope-and-Stand-Accessories
Cool Video showing all features that are maybe more important to XTC shooters.
Single handed scope head up/down and side to side operation is a great design feature so no need to break position to adjust the scope once in position.
At 1:32 in you see Dennis show how to swap the scope setup to be used on different sides of the shooter as desired.
True one size fits all and very sturdy so your quality scope doesn't crash to the ground if bumped or in windy conditions.
Any even fairly expensive / quality spotting scope deserves a good and solid stand.
Chad, I agree as others have said above any of the TSN1, 821M or 82SV will serve you well so you should just go with whichever one you find a best deal on if you can find a decent deal on a used one.
My primary spotting scope is an 821M with a 1" polecat head that I have had for years.
My backup / new shooter loaner spotting scope is a Celestron Regal M2 65ED.
The glass and brightness on this is every bit as good as my 821M when properly focused for picking up mirage. Only slight downside is the rotating band isn't as sturdy as the Kowa's. It's not bad but there is slight play in there on the one I have.
They are an awesome value and many people in my area never upgrade from these. scopes
https://www.celestron.com/products/regal-m2-65ed-spotting-scope
Currently $499 at Optics planet but you can probably find cheaper searching around and / or Amazon
https://www.opticsplanet.com/celestron-regal-m2-65ed-spotting-scope.html
One shooter / friend has the 80mm Celestron ED and it is quite a bit heavier / bulkier than the 65 and you are hard pressed to see any image quality differences when comparing side by side on the range.
Many used cheaper / lesser quality spotting scopes are posted for sale as people upgrade to what you are wisely looking to go to 1st.
Good deals on used Kowas do come up from time to time so Jump Quick when you see one..
Recommended Scope position in Prone shown at 1:21 in on the video below.
At 2:18 in there is a lesson on how the spotting scope in the proper location can save you points from wind / mirage changes. and Checking mirage from position without breaking position at 2:30 in.