For me it was the first time I beat (the guy who shot me) to death in (his base of operations) the first time I ever saw him, in front of everyone, even with no holdout weapons. It was on my unarmed/melee character and I'd just picked up the Super Slam perk. What a rush!
And then from there, generally, the high tech cyber punch weapon, the same one Veronica has ... it just feels so good, even if there are better unarmed weapons. The 2 of us just smashing people between us to meat ... so so good.
Also, Spiked Knuckles. YES!
As for shooty weapons, I really like the feel of the Cowboy Repeater. Hunting Rifle *is* better but Cowboy Repeater *feels* better. I love Ratslayer too. Ratslayer feels like magic.
I also enjoyed the hell out of the All American. I felt so awesome with it, tho I've barely had a chance to use it because the character that has it has no repair skill and few caps to repair it and I'm re-making him anyway.