Guns - This Machine. I love the M1 Garand, plain and simple. Plus, the ting! at the end of a clip, classic!
Energy Weapons - YCS/186. Why? Absolutely wrecks grouped enemies with Laser Commander and Meltdown.
Melee Weapons - Cosmic Knife, Super-Heated. Randomly setting enemies on fire is hilarious and AWESOME. This or the Shishkebab.
Unarmed - Ballistic Fist. Nuff Said.
Explosives - Grenade MG w/ Highspeed Motor. I LOVE raining explosive death down on my enemies.

My fav weaps would have to be That Gun, 12.7 SMG, Grenade machinegun and the chainsaw.

there's so many good weapons in this game.

this machine with hand load rounds, absolutely the best. M1 garand is one of my favorite rifles anyway, and like another has said, the clink at the end of the clip is classic. i typically carry this machine or the automatic rifle to get me out of any bad situation i might find. either one can clear out quarry junction or deathclaw promontory without a second thought.

i started listing some weapons i like and i realized i like just about every weapon in the game. even the lowly 9 mm is a great weapon with the mods. i love the scope, fast rate of fire, and the extended mags make it a mini service rifle. everytime i go to my safehouse i pick a different weapon to be my primary. they're all fun to use.

Gauss rifle and YCS/186 for me. I like the oomph each shot has, the reload animation where player basicly rams a new MF cell inside the weapon and the shockwave from the bullet when it ruins someones day. Also gauss rifle being pretty much miniaturized version of my fauvorite real world gun, http://www.youtube.com/watch?v=Z8DehAUimRA sure helps a bit too

I prefer the classics..

Mine is the ratslayer it so amazingly ninja, i like creep up on a ghoul and i just shoot its head and it starts to jiz everywhere and im like OH YEAH!

I'm split:

The .50 AM Rifle, pair that bastard up with the hand-loaded Match Grade ammo and I was busting Deathclaw skulls as soon as I could see them when scoped in.

Close in, I was using an Assault Carbine, despite it's low damage at higher levels, the high speed and substantial quantity of ammo was enough for me to start playing tactically and use cover.

EDIT:http://www.youtube.com/watch?v=fCtD3OJ-_Es

This is a hard one, but I would have to go with the fully modded laser rifle...

Ballistic fist, max repair, with the slayer perk. Turns you into a living weapon of mass destruction. Pair that combo with a companion who can hit what he/she aims at at a distance (I have good results with Boone and Arcade), and you're tough to beat.

Another good one is the 12.7mm SMG, silenced. The spread may be bad, but it hits like a sledgehammer.

Guns: Lucky or Maria simply because I like the color schemes, designs, and the means/time of obtaining for both those guns.
Explosives: Anabelle. Took out the entire Deathclaw Promontory (a.k.a. saved my ass) so I kinda love this weapon.
Unarmed: Love and Hate; I just like these for some reason.
Melee: Knock knock just the design alone is awesome.
Energy wep: Laser RCW (energy tommy gun) for the mobster in us all.

I wonder if in a future game they will allow dual wielding for the smaller guns?

I like to take a minimal amount of guns, so I only use a select few.

Assault Carbine - Now with 5mm ammo at -10DT, this gun is just BEAST. You don't even need AP ammo that much anymore. But 5mm AP on Deathclaws is like automatic death.

.357 Revolver - I use this with the Cowboy perk and just LOVE to fire it. A great sidearm because of the common ammo type, and its pretty good DAM. Also, it's a pistol, so no speed penalty.

All-American - I thought Cazadors were hard before I got this gun. Great DAM and DPS, also, it's semi-auto. Vault 34 was worth it, for this gun, and Vault 34 Security Armor.

Also, Laser RCW - Just looks awesome. I don't care that it looks like a Thompson, it just looks like an awesome gun.

I don't use it anymore, but 9mm Pistol - I just really like this gun. Really common ammo, looks like a Browning Hi-power, and has a great rate of fire. I kinda wish it was more powerful.

My fave is This Machine. I love how it reloads with the sharp Ting!, its suburb Damage Per Shot and Critical Damage, and is one of my favorite real-life rifles the M1 Garand. The Marksman Carbine is my second pick. As soon as I repair it, I think it'll be a beast weapon! My third fave is That Gun. Its size is no match for its excellent DPS. I have no actual energy weapon fave or shotgun fave or Unarmed fave. But I'll decide at later playthroughs. I'm also considering the Assault Carbine, as its ammunition isn't that expensive, unlike 5.56mm rounds, and its DPS is really huge!

this of course
http://fallout.wikia.com/wiki/Multiplas_rifle

With this life saving E. gun i assaulted the BOS bunker, the Quarry and the promontory, on hard, and won
http://fallout.wikia.com/wiki/Multiplas_rifle

i'll say it's a tie between the Bumper Sword and the Hunting Revolver. But i do love the variety of all weapons in NV... especially with the addition of crafting & ammo types.

Ballistic Fist FTW!! :mohawk:

Lucky.

Fast-firing, accurate and absolutely deadly on a high-luck Cowboy with Hand Load ammo. And all that for very VERY cheap ammo and repair costs.

Ratslayer is #1 overall. Will easily take out 90% of enemies in a single shot, or two at most.. For bigger prey, Brush Gun usually (with the Cowboy perk) or occasionally This Machine.

Of course, I've played several characters, each if whom specialized in different weapon types. They all loved: Q-35, Holo, Oh Baby!, pushy, Thump Thump and Mercy.

With the recent (recent ish) patch, I'm strongly considering a heavy weapon specialist. Take CZ57 for a "spin"

Fully modded Hunting rifle is a god but in ther form of a gun the ONLY downside to this huge damage slowly breaking fast action gun is the high VATS cost.

They did its called 5.57mm Pistol.

Plasma weaponry

My favorite kind of play through! It is very skill intensive - max out Guns, Energy and Explosives. But you will mow anything down in he Mojave! Grenade Machine Gun, CZ57, Minigun, LMG, Gatling Laser, Flamer, Heavy Incinerator, Plasma Caster and when you need to "snipe" the Tesla Cannon! Very, very fun.

6 Deathclaws,One Courier, One 9mm pistol,278 bullets.............6 dead Deathclaws

I just started using Throwing Spears and I absolutely love them.
Sure it's hard as hell to aim well with them but when I get in a successful sneak attack it's so satisfying.

A tie between the Zap Glove and Lucky.