Laser vs Rocket Launcher
Not such a simple answer.
Lasers generally have more attack power, but take longer to charge up. Lasers are best if you can raise your opponent up with either a lifter or a forklift, and just fire at them. Rockets shoot much faster, and if you can't raise your opponent or have the health required to survive a few blasts for when your laser charges, you're as dead.
Rockets fire once every second, but have lower damage. Their fast firing speed makes them an almost necessary weapon to have, just so you have some range and can fire quickly. Using a repulse or backpedal can prove very useful. If you repulse, your opponent will come back towards you... and run right into a rocket. Using a backpedal has a similar effect, it moves you back, and as long as you can balance or if you have a double rocket, they'll run into it again.
It's really up to you. Personally, I use rockets because they fire faster. Tell me what you think in the comments.