Uberti is good quality, from what I've seen. Your most versatile caliber is the .357, since you can shoot .38 specials in quite a wide variety of loadings, and the ammo is cheaper.
That said, I really like the .45 Colt. The big hole, the big boom. You can get some pretty good deals on ammo if you look around. Some of the "cowboy" loads are cheaper and easier to shoot, since they're powered down.
I took my son-in-law shooting a while back and let him start out shooting some cowboy loads in my Vaquero. Then I loaded up some hot self-defense rounds for him. It's quite an impressive difference.
As far as the weapons configuration, the bird's head grip is quite comfortable to shoot, with the additional benefit that there are no sharp edges on it, so it's comfortable to carry, in a variety of rigs.
The 4" barrel is also a good choice in a holster gun. Any longer than 5-1/2" starts to get bulky.
And you know, a short barrel, single-action, revolver with bird's head grip is just, well, cool. Here's mine: Ruger Vaquero .45 Colt, 3-3/4" barrel.