It sounded like you were looking for a New current production rifle?
The T/C's are totally out for me with that ≈ 1" long QLA. They don't make the Omega any longer, you can't even get real stainless on most of their models, and definitely no nitride treatment. The Encores all required trigger and spring kits for best performance. Can't get a fast twist .45 caliber.
The Knights require a minimum of a breech plug upgrade. Some require a bolt adapter kit as well. Bestill ignition upgrade for optimum performance.
The CVA tip-up rifles require a minimum of Blackhorn breech plug. The Paramount will shoot Blackhorn 209 in stock configuration, but will have leaky ignition at some point. Currently there is an optional 209 primer breech plug, or the ASG. LRMP ignition upgrade for optimal performance.
Traditions breech plugs might work for a few shots, but are far from ideal. They need modifications, for optimal performance. No stainless, heavy triggers. Can't get a fast twist .45 caliber.
The Remington UML cannot even use Blackhorn 209 in the OEM breech plug, without voiding your warranty. They also need an expensive upgrade for the ignition system, for optimal performance. Can't get a fast twist .45 caliber.
The "Best" Blackhorn 209 rifle that needs no work, hasn't been built yet, IMO.
Maybe Western Powders will build their rifle and breech plug they have patented, someday? But obviously not today!
Maybe SSK/Lehigh will build it for them?
Time will tell.
One of the best deals on a 1:20 fast twist .45 caliber IMO, is converting a CVA Scout .45-70 into a muzzleloader, by adding a good breech plug. You can buy the rifles as low as $325. They come with a brake and thread cap. Have excellent triggers right from the factory. Come with Weaver style scope base. Have quick takedown forend. Just add the breech plug conversion of your choice from Hank, ASG, Bestill, and you will have not only a Blackhorn 209 shooter, but one capable of shooting exotic powders as well.
I guess it all boils down to what you want to do with the rifle? Hunt, Target shoot, or both?
Do you want a .45 caliber or .50 caliber?
Fast twist, or moderate twist?
Saboted bullet, or sabotless shooter?
209 primer, or LRMP adapters?
Blued, Stainless, or Nitride Treated?
New or used?
Budget / Price Range?
CVA makes the Accura LD in the 1:22 fast twist .45 cal, but you would need to purchase a Blackhorn 209 breech plug for it, unless they include it with that rifle now? I'm not fond of the goose neck and dog leg stocks in the Accura V2's, or the T/C's.
The Accura MR would be my first choice, but they aren't putting the 1:22 fast twist .45 cal barrel on them yet. Those stocks on the Accura MR / PR fit me like a glove.