PLC.

Plasma Cannons require the most skill but are more of a niche AV weapon, being almost useless against good dropship pilots, and only marginally effective vs Armor.

Forge Gun requires a lot of skill to excel at, and has the advantage of being good vs infantry if you're also good.

Swarm Launcher is the most rewarding since you'll be collecting WP literally just for looking up and pulling the trigger. It's very relaxed and more focused towards casual players, so if you're looking for easy points then Swarm Launchers are the way to go.

thank you ill possibly go for the Forge then, i like the challenge and the ability to snipe infantry

Forge Gun has the most satisfying feel to it, however keep in mind that you'll be tied to heavy suits while using it. For this reason, a BPO LAV is strongly recommended in order to keep you mobile (unless you've got bank, then a normal LAV will be fine). Or you can just camp a tower or objective to help deny any vehicles in your radius.

If you've never forge gunned before, it's common knowledge that the Assault Forge Gun is the best all around FG, while the Breach FG is best if you have a squadmate with AV who's actively working with you to time your shots together. Try to avoid the standard FG. Also, the Breach Forge Gun roots you in place while charging, but you can jump around still to make it harder for things to kill you while you sit there holding a giant KILL ME sign.

At least against dropships, try not to shoot them until they're close to you and / or hovering. The closer they are to you, the longer it will take them to escape your optimal, meaning more shots for you. Aim at either of the two engines on the back of a DS for massive bonus damage. Hitting them while they're hovering will give you the optimal amount of time to kill them since they have to accelerate away, and if their afterburner is on cooldown or if they just aren't running one, you can usually land the kill before they fly too far away. With that in mind, good pilots don't hover much these days, so use your best judgement. The main reason I say don't shoot too early is because as a pilot I love nothing more than a long range forge gun shot as the first shot, since I now know where to avoid and can flee with ease.