The Walker is an Armi San Marco special engraved version.
The 1860 Army is a Uberti.
The Navy with the squared trigger guard is a Colt.
The rest are made by Pietta.

I think they are all pretty comparable but agree that the Ubertis are a little better finished. It is a Cimarron retailed pistol and I think they may specify better finish from Uberti.

https://www.cimarron-firearms.com/

The Colt is, of course, overall a nicer pistol except the nickle is spotting and flecking so to get it back to 100% those parts would need to be replated. I bought it that way at a discount.
No idea if Colt actually manufactured their guns or got the parts from Italy.

The Pietta prices run about 20-25% lower than the Ubertis but on the second hand market none of them are what I'd call expensive.
With guns like these - which will be shot a lot and scrubbed clean a lot and holstered a lot, I think a well used example is actually preferred to a new one, especially when they are so cheap!

The Navy and Army are so good in the hand and are such natural pointing pistols, once you get practiced, it's not too hard to outshoot the guys at the range with their semi autos.