I have to go with Veronica because of her winning personality, kick ass punching arm, and dreams of getting a dress, what a lady :D

I like Cass cus earning her second perk requires so much bridgeburning. Boone is almost boringly efficient and he never says anything interesting. 

Boone rapes buttholes.

Boone is the awesome. I traveled with Cass for a bit and Veronica I think wants to kill me (I made an oopsy in her base LOL!) and the others are ho hum. Boone lets me wander the wasteland carefree (well except for the quarry) and even carries all the incinerators for me.  I actually think I might marry him one day. Have a nice wedding at the Tops or something. 

Veronica with a Ballistic Fist fuckin WRECKS shit.

Raul because 

HE KNOWS HIS PLACE

I like rolling with both Boone and ED-E. I love ED-E's perk and as soon as you fire at a target, Boone picks them off before you can say "headshot".

I have Veronica right now(though she seems to have wandered off somewhere).  She is a beat with her Ballistic Fist, but can't do anything but unarmed combat.  I have heard great things about Boone just wrecking everything in site, so I am going to go back to town and pick him up.

Haven't played the game yet but right now Raul's looking pretty alright

Cass, mainly because she has the best dialogue in the game. although I am finding Veronica super awesome. actually most of them are...

Veronica is my favourite but I can't use her as she gets stuck at lvl 12. Her HP stays at 215 while everyone else is 300+.
 
Currently using Arcade Gannon with Gauss Rifle + Remnant Power Armor. He kicks ass.

Boone obviously 

I am loving ED-E as a companion.  Also, I look forward to travelling with Felicia Day as Veronica.

Boone

V is still my Favorite with Boone a close second. I loved her "Loyalty" Mission and she fits my play style the best.

I love Veronica, her punching powers are awesome. Plus let's face it, who wouldn't want Felicia Day following them around, I mean:

*Puts on beret* 
 
... 
 
*People standing in front of the dinosaur suddenly explode* 
  
 
And from that point on, I liked travelling with Boone.

Arcade is probably my favourite so far (I just picked up Veronica and haven't met Raul).  Getting the team back together for his side quest was neat, and has sweet loot.
 
Cass was alright until a part of her sidequest bugged and railroaded me into taking a course of action I didn't particularly want to take.  Boone is fucking dull, plus a total pain in the ass if you ever want to go talk to the Legion (which you should because Caesar is awesome).

Rex is also kind of bad ass,even if he's no Dogmeat.

Boone rapes peoples faces from distances with sniper rifles.

Can I change my vote to Fisty? 
 
He should be a companion.

I loved rex and boone until they decided to disappear and never come back

My favourite companion is Mr .44 Magnum. He never questions me, he's always by my side and he gives me the blowing-your-head-clean-off perk.

" My favourite companion is Mr .44 Magnum. He never questions me, he's always by my side and he gives me the blowing-your-head-clean-off perk. "

Raul for the most useful perk of them all and hilarious personality. Also  @Vodun: Don't talk shit about the mysterious stranger! I was on black mountain and was about to be pulverized by a super mutant master when he appeared and saved my ass on one bar of health left.

Just finished my first play through.  I had one companion briefly.  The Brotherhood of steel woman.  Veronica?   I let her follow for a while, then walked out into the wasteland.  Shoot her with my combat shotgun using beanbag ammo.  To knock her out.  Crippled one of her legs with my hand gun.  Then waited for her to come to.
 
She then attempted to attack me, but I kept my distance.  Basically, kited her until some large bugs attacked us causing her to defend herself.   Killing the bugs going for me, I  backed off further and watched as she almost died.  Had to help her to get the kill, then blew her head off as she limped over to me.  
 
 I tried to get Boone later.  But he got angry at me for making him kill his friend for no reason.  So i cut his head off, then proceeded to slaughter the entire community he had been working so hard to protect.  
 
Guess you could say, I'm kinda a loner...

One of my most memorable moments was splattering an entire battalion of troops with Boone, Rex and Oh Baby! before leading Caesar and his posse of ass-fisters out into a pile of C4 planted at his front door. Veni Vidi Vici mothafucka!

" Arcade is probably my favourite so far (I just picked up Veronica and haven't met Raul).  Getting the team back together for his side quest was neat, and has sweet loot. Cass was alright until a part of her sidequest bugged and railroaded me into taking a course of action I didn't particularly want to take.  Boone is fucking dull, plus a total pain in the ass if you ever want to go talk to the Legion (which you should because Caesar is awesome). "

I love Rex. He's such a beast, especially with the brain that powers up his attack.

Boone because I barely had to shoot anything myself.

I must like ED-E, because I've lost him like four times and I keep forcing myself to make him come back. I haven't finished all of the companion's stories yet, so I can't really judge on that front. 

Cass because I like getting drunk to boost my stats and there's just something awesome about a whiskey loving cowgirl with a shotgun.

Veronica because she is awesome and wants to be pretty.
 
Boone is cool but he just snipes everything. I feel he is OP and needs a nerf lol.

Boone is the best companion, but Arcade is by far my favorite.