Here is my $.02 worth.
First, if CAS is what you plan to do, before buying a rifle, select what handgun brace you are buying. Don't buy .45 six-guns and then a .38 rifle, for example.
Next ask yourself if you want something authentic to the era, or if you are gamer looking to win matches. If the former, you might find yourself buying .44-40 or .38-40 and hand loading, or for a close approximation, you could enjoy a .45 Colt (as I do).
If you are a gamer, there is only one choice. Buy a .38/.357. Period. No top competitor is using anything else. Just bear in mind, it will not double as a credible hunting rig in .357 in a toggle-link action.
So let's assume you are buying a .38/357 since you plan to plink and maybe do CAS. The next consideration is do you want a rifle (more accurate, faster to settle back on target, heavier to absorb recoil, but swings slower) or a "short rifle" which is something that never existed in 1873: a 20" "rifle". Cutting to the chase, all the top CAS competitors, if they run toggle-links, run "short rifles" these days. Gamers have realized fast swing action to targets across an arc of fire gives a slight edge over a longer gun with slightly more accuracy and slightly less muzzle jump. Also, FWIW, I prefer the 24 full rifle and don't win matches
Now for options. Winchester/Miroku is making an 1873 clone now. I've not shot one. It has a rebounding hammer and a tang safety and costs a good bit of cash. If you want to race the gun, you'll be removing the safety and the rebounding hammer (a gunsmith job if you want it to still run well afterward). I do not believe there are many race parts out yet for the Winchester, it's still pretty new.
You could also buy an original and tune it up. This will get expensive fast - I don't recommend it.
SOME of the Italian guns are a good buy. There WERE some Chaparral Arms and Navy Arms guns on the market. Avoid those. The Chaparrals had a poor reputation for reliability, fit and finish and don't take Uberti-style race parts. Similarly, the older Navy Arms guns, though made by Uberti, were put together long enough ago that some important things like the elevator blocks are not interchangeable any more.
So now we're really down to the "good" guns with "good" after-market parts support. These are the Taylor's & Co, Cimarron, and Uberti guns. The first two are made by Uberti and are re-branded by the middle men whose name are on the guns. Both Taylor and Cimarron tart up their basic models by adding a Wolff spring kit and in some cases they swap the european walnut stocks for black walnut or gum wood. They also bump the price up a few hundred bucks for that work. They also offer race-ready models for nearly double the price of a basic gun - these are a good buy if you know nothing about short-stroking and tuning a CAS rifle.
In my view, get a basic Uberti for the best price you can find if you intend to shoot CAS. The things Taylor and Cimarron improve on their basic model are all things you will want to redo with even better parts if you ever get into CAS, and the basic rifle is fine right out of the box for plinking.
If you decide CAS is more of an aspiration and not something you will ever get to, the Winchester/Miroku is a fine gun that will have some collector value some day, while the Uberti and clones will generally be shooters until they are worn out - I doubt anyone collects Italian replicas.
I wrote up one of my CAS builds on a basic Uberti 1873 here - it might be worth a read so you know what you'd be in for.
http://www.canadiangunnutz.com/forum/showthread.php/863902-Uberti-Winchester-1873-clone-can-we-improve-it-YES-WE-CAN!?highlight=uberti