The differences between the Dragoons are essentially cosmetic, so there's not much to recommend one over the other. The change in cylinder stop notch shape between the 1st and 2nd models was a minor improvement, but that's about it.
The main difference between a Dragoon and what you have is substantial: it's a significantly bigger gun. It's quite noticeably heavier and the grips/grip frame are bigger, so it's pretty much a two hand hold gun. It also holds another 15 grains of powder, which is substantial; not only can it load much more powder, it's capable of withstanding the heavier shock, so you can reliably fill it up and bang away, making more smoke and flame than ever before.