Here we go, #1 PC Gaming Hero on my list is noneother than JC Denton of Deus Ex fame. Deus Ex turns out to be one of the only games I know where it has received universal acclaim amongst my friends - and that's hard to do since I have an eclectic mix of friends, some only liking particular genres.
Considering the entire game of Deus Ex is just one big conspiracy theory on top of another, this is a nerd's dream game - and your character, JC Denton, is like the world's greatest detective - yet augmented with nanites and a cool stash of weapons to boot!
In terms of character, well that depends on how you play the game I guess - a bit like Mass Effect, you can take a paragon approach (limiting casualties) or a renegade approach (guns blazing, killing everything you see). Regardless of how you approach the challenges in the game though, JC Denton is out there to stop the evil Bob Page who wants nothing less but to take over the world. JC Denton turns out to be a beacon of hope in a dystopian, cyberpunk future where megacorps have total control of world governments.
Most of all though, unlike many PC gaming characters of the Duke Nukem variety, JC Denton is intelligent. How many PC Gaming characters do you know can on a whim walk up to a bartender and debate the political systems of the West vs the East (and yes, the bartender's voice acting is terrible)? JC is an ultimate nerd, but one that can back up his ideals with action (whether it's with stealth or bullets, is up to you). This I think is why JC Denton is so appealing to PC gamers and is why he completes my Top 10 PC Gaming Heroes list at #1.