Gauss gun is the highest dam regular gun in the game. With Max Charge shots it can do 210 damage per shot. The other two most powerful weapons are the unique Gauss and the Alien Blaster, both energy as well. Downside to the Gauss being that it still has the VATS bug from FO3.
Lasers aren't the best, true. The laser rifle is (according to the lead developer) the most accurate weapon in the game, despite its low damage and having the only upgrade in the game that makes a weapon even more situational. Laser RCW works wonders against light armored foes, though not their heavier buddies.
Plasma is decent enough. Just don't get so upset about laser not being very good.
Decent enough?
The plasma rifle is so badly outclassed by the cowboy repeater, both supposedly being of the same tier since their skill requesites are both 25.
Cowboy Repeater fires soooo fast thanks to the inhumanly fast lever action (seriously... how could that have been missed? I can fix it so easily), The cowboy repeater can also load Handloaded rounds, which are essentially like Overcharged shots, but don't tear the gun up and also have a modest DT-piercing effect and are more accurate. It also uses only 1 cap's worth of ammo per shot (standard .357 is 1 cap per round) while the plasma rifle eats up 6 caps worth (MFC = 3c, x2 per shot). It uses 10 less AP per VATS shot than the plasma rifle, and also weighs 3 weight units less than the plasma rifle. The Cowboy Repeater also gets a 1.25x crit chance multiplier, making the 2x that the Plasma gets less meaningful.
The heavy plasma guns (Defender, Caster) may be good stuff, but the regular ones svck. They're so totally outclassed by Guns in the equivalent tiers, just like lasers.
Plasma Spaz? Wooo, now I can fire my svcky plasma rifle 3 times instead of 2 in VATS... while I could already fire the Cowboy Repeater 4 times. Still can't fire my Multiplas more than 2.
Meltdown? That makes crit kills highly dangerous to you, not just your foe, thanks to excessively large AoE and damage of the effect. You end up hoping you
don't crit kill them.
Vigilant Recycler? Despite my heavy-handedness with the Super Mutants on Black Mountain with my Multiplas rifle, I have not noticed any significant increase in the amount of MF cells recovered, certainly not enough to feed hungry plasma rifles.