I like using pipe guns / rifles. Even though I am around level 48 or so, I still use an automatic pipe rifle as my default weapon. It does not do a lot of damage (28 damage points I think), but I like that it has pretty high ammo capacity of 48 and I am overflowing with .38 ammo. Plus it is a pretty light weapon.
I got energy weapons, but I don't like the disintegration effects so I am waiting for the GECK so I can disable 'em before I use those weapons.
I haven't really done many missions in the game. I have mostly been exploring and scavenging for junk so I have not come across any really powerful / unique weapons yet. I'm more or less focusing on building up my 5 settlements.