Stage 2, for sure. the stage 1's as mentioned by chris are a regrind of a used stock cam, and in some cases, a cam that wiped a lobe off due to a failed lifter, and then been welded back up, and re-ground. While colt says they don't have any issues with their welded cams, there is lots of evidence of other big time mass engine rebuilders having higher failure rates with welded cams.
I'm sure either stage 1 or 2 would be fine, they both address the concave lobe issue that tears up the stock lifters... but I would prefer the stage 2...no idle quality issues, no real loss of low end torque or anything...and despite what RCD has on their website you don't need flycut pistons, as long as the rest of the valve train geomotry is right (Updated shorter pushrods, preferably corrected valve height, adequate valve recession-more than .020", and piston to valve contact shouldn't be an issue). No real down sides to the stage 2 other than the fact that it costs a little more.
I doubt there would be any real noticeable differences between the two based on their specs. I haven't seen seen where anyone has had dyno results with changing just one cam independently, no other mods, let alone changing cams out twice for back to back dyno results with stage 1 and 2. Just for the record, the cam gear is located in the back of the engine, thus requiring removal of the engine to remove the cam...and you'll have to press your old cam gear off, and press it onto the new cam (use heat, I can provide more details on that if you'd like).