Not making anything "new" in the last 5 years really shouldn't be a hold up. It's a muzzleloader you intend to hunt with. It's not important either, because it isn't true. They released the Peregrine just 2 years ago.
CVA has their place, but comparing them to Knight, that's a bit of a stretch. You will find people who got good CVA's that like them, and great for them. You will also find a lot of people who got bad ones. Barrel dimension and quality can vary widely on CVA.
Knight on the other hand is top shelf. Very few people get ones with bad barrels. As for accuracy, Knight has lots of national championships. As far as I can tell, CVA just won their first one.
That's just the two brands, very general overall quality. Both brands are exclusively modern inline designs, but both offer break actions, up to bolt actions. Knight offers more variety. In a quick 5 minute read through the Washington regulations it appears that centerfire primers like 209's are legal there. I don't see if it has to be "western" open ignition or not. If so, or if you have any chance of hunting surrounding states, then that right there I would lean strongly to Knight. It looks like CVA does make one open ignition option for the Optima, but I wouldn't want that one.
Mallard SX2 mentioned cleaning, which really depends on the model you get. Plus the more "modern" you get in muzzleloaders, the less user friendly they get in general. If you want something you can shoot every day and have fun, you should really be looking at a percussion or flintlock gun. I had a Knight bighorn, similar to the disc, and that was a nice balance. It was only two screws, and a breech plug. Then you just cleaned the barrel and breech plug. It was pretty easy. Something like the Knight ultra-lite, or CVA paramount are just going to be a PITA to clean, no ways around it. I'm guessing that's why a lot of guys turned to things like blackhorn 209 powder, so they can get away with very minimal cleaning.
This is just my opinion, but if I were not interested in traditional muzzleloaders, and wanted a new modern inline built for open sights that was accurate and dependable, I might have to lean to the disc extreme. The cost to accuracy ratio on that rifle is probably best there is. It has a good sight radius, and a good solid design. The only thing the ultra light really has on it, surprise, is that it's quite a bit lighter. At 6 pounds, I'm not sure I'd want to shoot that very much. If you just want to sight in, and hunt, it might be the better option. I can tell you from first hand experience, a muzzleloader without a usable ramrod on it is not a good plan. Yeah, ditching it saves a few ounces, and probably reduces some barrel harmonic issues. Those things might matter to someone pushing the extreme limits. Since you are limited to open sights, with some practice you can be making 200 yard shots. 150 and in being more ideal. At those ranges those things matter. Getting a good barrel that is accurate with that first shot is what matters. Getting good sights on there matters. Basic fiber optic open sights are poor for longer shots. Great for inside 75 yards. You will be wanting peep or aperture style sights. A globe sight is ideal for accuracy, but I've had mixed results using them hunting. I prefer an aperture and narrow front blade myself. But not having a ramrod when you need it right now, that's not something you want.
Having said all that, I think even better yet is to buy a used TC renegade or hawken percussion. They don't cost that much to find with junk barrels. Then you can choose if you want to go better for long range, or better for short range. Assuming you want more range, GM makes a fast twist barrel for these. Put a Lyman peep sight on it, along with preferred front sight. Alternatively you can send your barrely to Bob Hoyt and he will install a sleeve for less than most new barrels cost. You now have a rifle that is a dream to shoot, doesn't weigh too much, probably around 7 1/2 pounds, and is all around a much more user friendly muzzleloader. The barrel is held in with a key, they are way less fuss to clean. The icing on the cake for me is the trigger. Knight uses Timney triggers which are some fine triggers, but they just can't match a TC set trigger. A TC set trigger trips at just ounces of pull. The one and only "drawback" is they can't shoot the $160 per pound blackhorn 209 powder, not even with a 209 primer adapter.