Interchangeable or stackable?
Which is your preferred beam system?
I prefer the interchangeable system from Prime 1/2, because it provides a great variety of attacks that are accessible at any time. I also prefer the Prime 1 version over Prime 2 because this one is fantastically animated, with great sound effects. Although Prime 2 used the same basic design, the weapons themselves were boring and gimmicky.
The stackable beam system from Prime 3 is good enough, but before I played the game I was a bit worried about it's design being irreversibly changed whenever I acquired an upgrade. Say you hate the design of the Plasma Beam, you're stuck with it for ages until you get the Nova Beam. Fortunately, Retro did a good enough job on each one so that I didn't dislike any of them, with the Power Beam, Plasma Beam charge shot, and Hyper Missile being my favourites.