Fingers is right
The BEST replicas are the 2nd Generation Colts, available occasionally at gun shows or in internet auctions. I don't think anyone would argue with that.
But, since you said Pietta or Uberti in your title, we'll concentrate on those (Euroarms also makes an 1860 model, but they haven't reached the Uberti quality standard yet).
Yes, Uberti is still the quality standard, although as Hawg said, the latest Pietta offerings are very competitive in quality. Since they are generally also less expensive, they would seem to offer a better value for the money. We're talking about new guns here; buying used Piettas, especially those made before 2000 requires a different approach.
If you just plain want the best quality, and don't want to spend significant time looking for 2nd Generation Colts, I'd suggest the Cimarron Uberti is the choice. Quite a bit more money, but top of the Uberti line.