The 1851 Sheriff model will just be a shortened version of the standard 1851. Everything is the same except for the barrel length. I had one of them and the balance is good. The grip size is identical to a Ruger so if you like that feel, then Pietta is for you. If you want one that is closer to an original 1851, then Uberti is the better choice. The Pietta will require a little less fiddling to make it work optimally where the Uberti will have a short arbor that is best if you correct it. There are threads that show you how to take care of that. Once that is done, however, you will have a darn good pistol.
Also, if you want a .44, then your only option is the Pietta.
Either way you go, the Sheriff's model is a good one.