which sign....

Likes to talk about themselves the most, maybe even bragging to some extent... what they do, well known people they've done business with, and where they've been (in their mind) of particular importance?

if someone says leo i will slap them!

i've known some taurus folks that were quite materialistic and liked to boast about what they've attained in terms of accomplishments.

prolly aquarians but thats cos we know were that amazing.

It's not so much about being materialistic though... it's more like "this is what I do; this is who I know; this is where I've been; this is what I've done" NOT about what they have...

So, IMO:

Cap is out, because it would be more about struggles to get there...
Aquarius is a thought... they do tend to be full of themselves...
Pisces wouldn't go there in general, just in their own mind...
Aries can be quite certain of themselves, but I'm not sure so forthright about themselves...
Taurus materialism makes this sign not so likely...
Gemini's too busy with superficial topics...
Cancer, a possibility as they are concerned with how others see them...
Leo's, well, they do want to be in the limelight (sorry, MyEulogy90)...
Virgo's, don't want the attention on themselves, too reserved....
Libra's, on the other hand, like to brag to compensate for their feelings of insecurity...
Scorpio's are probably more self assured and would not feel the need to go to such lengths...
Sagittarius', well, they're more likely to talk about others...

I'd say Libras
ARIES: sure, they love to brag about their most recent & past accomplishments but then again so do most people.
TAURUS: They're pretty good at letting others show their narcisstic sides; but oh Lord, once a Taurus actually gets going, it's like they never stop. Taurus' are good at making the world feel they are very much needed
CANCER: They love to talk about their feelings but only when something/someone triggers that side of their personality. It's not like they just get a kick out of rambling on & on..BUT, if a person asks them a question or makes a statement that hits close to home for them, oh boy...they're another sign that keeps rambling on & on once they've gotten started.
LEO: THey are more physical braggers. They let their quests for attention do all the talking for them/speak for itself. They'll verbally brag about themselves if need be
VIRGO: They usually go on about themselves if someone tries to take away their credibility or tries to understimate the power they have over anything
PISCES: Once they get going, they never stop either. 1 good thing about this sign though is that they atleast allow room/time for the other person to brag about themselves too
SAGG: Sagg's just want to live life & let their "living" speak for itself. Sagg's brag about the rare & adventurous things they feel everyone else is too ashamed/boring to do
AQUARIUS: I'm not even going to lie; once we get started, it's a never ending saga. But even with us Aquas, we'll let someone else have the spotlight; hell, we'll just find a trickier way to get "ours" later; it's almost as if Aquas are mentally conceinted--in other words, we're not ashamed to admit that our mental capabilities are awesome!
CAPRICORN: Sometimes they brag about themselves as a way to make themselves feel above specific things; but they aren't usually just down right full of themselves
SCORPIO: No comment ;`)
GEMINI: Oh man, do they EVER shut up!?!