I personally like the Heavy Machine Gun and the Lock-Laser. 
 
My least favorite weapon is the LFE Gun. It's too slow for me. 
 
  

I like the gun that turns into other guns. I'll admit I havent played it, but that gun animation is sweet even at a distance.

"  I'll admit I havent played it, but that gun animation is sweet even at a distance. "

I really like all the guns in the game except for the lfe and that disc gun...
 
The heavy is good for short range and the assault rifle is really good for long. Its a great mix of guns, imo.

The ones I try to always keep with me are the assault rifle (for taking out regular dudes and shooting weak spots), the LFE gun (for getting big guys the hell away from me and/or interrupting their attacks) and the disc launcher (for cutting Romanovs in two).

The one I like firing the most is the Rocket Launcher. It's got too limited ammo to be worth carrying around, though -- when I see one I just pick it up, unload, and then quickly switch back to whatever weapon I traded it for.

"I actually really like the  assault rifle it's way more powerful than the heavy gun for some reason. "

" @Axxol: I thought it was the way I upgraded them but theyre both fully upgraded. I seem to be able to take out the bigger enemies in maybe 1 1/2 slow downs but the heavy gun always takes longer, maybe two. it's possibly how far I like to stay away from everything, I dunno, I have just had much better results using the assault rifle. "

" @Axxol: I thought it was the way I upgraded them but theyre both fully upgraded. I seem to be able to take out the bigger enemies in maybe 1 1/2 slow downs but the heavy gun always takes longer, maybe two. it's possibly how far I like to stay away from everything, I dunno, I have just had much better results using the assault rifle. "

No love for the shotgun? It's brutally efficient at close range, especially against the bigger guys.

I like the LFE gun.  Its a good combo weapon with the assault rifle.  Slow Down time in a group of enemies then fire the LFE to knock them down finish them off with Rifle.

Lock-On laser for the win.

I almost never use the LFE, Disc Launcher and Lock-On Laser although I'm beginning to like the Disc Launcher.  The Shotgun? It's been handy in a pinch on a couple of occassions but it's my least-used gun.  Lock-On Laser is pretty weak but is a cute thing to pull out if there are some rank & file robots mixed in with a boss fight.

I like the assault rifle just because of its ammo capacity (both per clip and per pickup).  I upgraded it several times more than my other weapons because of this and that's made it pretty useful, though not so much against bosses.  The LFE is a great gun IMO.  If an enemy gets too close, the LFE will finish him off way faster than any shotgun and maybe you can aim it right to knock over a Romanov, too.  I'd say my favorite weapon, though, is the disc launcher.  It isn't always the right weapon to use, but if you've got a line of enemies, it'll make short work of them.  That and the no-overheat melee attack it gives you.

LFE. Love it.

Also this game has like 8 different automatic rifle types. I can never tell them apart, lol.

The game is out yet? Does anyone know if GB are planning to do a QL or a review of Vanquish? 

"

LFE. Love it.

Also this game has like 8 different automatic rifle types. I can never tell them apart, lol.

"

Dude i swear there's like 20 assault rifles in this game.

(honestly i don't know. I would have to check, but i think there's more than 2. Not saying that a surplus of automatic rifles could ever be a bad thing at all.)

SHOTGUN!  
 
also the Disk gun gives you free Melee attacks! you wont overheat!