To the poster that said there is no .44 Mag Vaquero, wrong. (There was the original large frame Vaquero in .44 Mag.) Instead, there is no such chambering in the current production guns, which are the smaller mid-frame New Vaquero (large N). Ruger (and vendors) has taken to confusing in the past few years by calling all current production New Vaqueros just "Vaquero," a moniker which is/was supposed to denote the large Blackhawk frame but in fixed sight ("cowboy") form. All but the oddity .44 Special NVs say "New Vaquero" on them and not just "Vaquero," and they're all on the same smaller mid-frame as used on the 50th Ann .357, and .44 Sp and .45 Colt Flattops.
Though long discontinued (other than occasional special distributor runs), the original, large frame Vaquero is available in .44 Mag on the used market. Functionally and strength-wise, they are the same as the New Model Super Blackhawk.
To the OP's question, I'd suggest Ruger. As someone else said, Uberti makes a nice Colt clone for the "cowboy" look and feel. I've got a Cimarron Model P that I really like. In something like a .44 Mag, I'd go with the Ruger, and have/had no qualms whatsoever with the New Model guns.
Regarding internal "safeties," they may say it's ok, but I wouldn't ever trust any non transfer bar "safety" in the Ubertis for loading the full 6, and that goes double for any older Uberti. I'd treat them--old or new--like a Colt SAA - load five and stay alive!
I too have been intrigued with the Uberti Callahan, "just because." It's got that unfluted cylinder--which in a fixed sight gun gives it that old 1847/51/58/60/72 (etc) look--and a non-standard 6" barrel length (versus the typical SAA/clone's closest apples-to-apples of 5.5"), which is interesting as novelty features at least and IIRC unique among Ubertis to the .44 Mag chambering. The gun also sports the longer 1860/"Army" grip--vesrus the SAA's '51/"Navy" grip--as well, unique among most other Ubertis and clones (they've got a few other models with...). Kind of a cool gun
...BUT, if I only could have one .44 Mag, it'd be the Ruger IMHO.