Well, the only two entities producing 1873 replicas are Uberti and Miroku (the firearms manufacturer in Japan that makes these for Winchester). There are pro's and con's for both. You'll find the Miroku to be a superior product in terms of quality of manufacturing. I have examples of Winchester '66's and '73's from both concerns, and the Uberti rifles required a LOT more work to tune up and were more likely to have small flaws, burred internals, and left-over machine swarf inside. HOWEVER, the Uberti guns are more authentically constructed. Miroku re-engineered their toggle link rifles, and one can honestly say that these engineering changes included some improvements. But they did change the shape and contours of some of the internals, and purists don't like this. The Miroku lever throw is a bit shorter than a stock Uberti. It isn't much, but is shorter than an original Winchester as well, and that was enough to disqualify them for NCOWS. So if you plan on doing any cowboy action shooting with a Miroku, you'll have to stick to SASS.
Uberti offers much more variety than Miroku, and more calibers also. Miroku started out their '73 production with .38/357 only, followed by .44-40 the next year and eventually offering .45 Colt. They did the same with their '66, but they're long overdue for a .45 Colt in that rifle. I'm beginning to doubt that they'll ever include .45 Colt in their '66.
Prices are a little lower on Uberti rifles, but street prices are very close--close enough that the higher quality of Miroku construction more than accounts for that. Miroku rifles should cost more than they do, in my opinion.
Regardless, although it took a lot of work to tune up my Uberti rifles, now that I've gotten them tuned and slicked up to my satisfaction, I've actually begun to prefer them to my Miroku rifles a bit. My tune-up jobs turned out a little better on the Uberti rifles, which I attribute to their needing a more thorough job done to them. So much about them was rough that everything on them got some work, whereas I left a lot of stuff alone on my Miroku rifles. Consequently, the Uberti ones ended up a bit lighter and smoother to operate than my Miroku rifles, even though the Miroku rifles were much smoother out-of-the-box than my Uberti rifles. And I also prefer Uberti's more authentic construction.
Good luck on your decision. If you choose a Uberti '73, and you don't know how to slick it up yourself, set aside about $300 and send it off to one of the many outfits that specialize in tuning them. The end result will be a fantastic rifle!