What's the difference between the 29-2 and 29-3? Is one better than the other? Which one would you buy?

29-3 (1982) Eliminate cylinder counterbore & pinned barrel. Cylinder length 1.69"

Personally, I like the pinned & recessed version, but I don't think that it's a big deal unless you are a collector. Either will do as a shooter.

Here is a link to a history of the Model 29 and Model 629 that explains S&Ws .44Mag by John Taffinthe differences.