I always preferred using plasma weapons to laser weapons in new vegas until i got the laser commando perk after which laser weapons were in general superior imo. But i still think plasma is the coolest weapon technology in fallout, aesthetically.
Energy weapons in general just really tickle my fancy, i love role playing a genius scientist type who is proficient in maintaining and using them. Also there's nothing more intimidating then a Gatling laser wielding power armor juggernaut.