You may be interested to know that I have at least familiarity and definitely interest in the following systems (and some notes):
Pathfinder (and possibly d&d 3.5, but I'm limited in resources there and might make mistakes where there are differences)
Shadowrun (4e or 5e): I think 5e is a bit more balanced plus less confusing matrix rules, but 4e has Chummer and a much broader variety of resources, so they tie at least for now.
GURPS 4e: I like GURPS for SUPERS campaigns. Not quite so fascinated with the intricacy for more generic fantasy though.
Starwars Saga edition: Jedi, the force, lightsabers, bounty hunters and galactic politics. Need I say more. KOTOR particularly got my attention. Other starwars systems I don't have.
On me as a Player:
I like things to feel plausible or consistent within the setting. I value characters that feel organic and suited to the setting, I like characters that grow with the events that befall them, not simply in power but in personality. I shy away from the phrase 'Serious Roleplay' because that makes the whole thing sound droll. I tend to be on the optimistic side of things when it comes to my characters, things are rarely perfect, but I don't tend to got for 'dark and troubled past' as my first option either (Unless the game is shadowrun where anything else would usually stand out more).
All that said above, I am also a mathematician and optimisation comes naturally to me. I am not a Munchkin (my goal is for everybody to have fun, players and GM alike) I tend to develop an optimised build first, then step things back to match the character that inevitably materialises in my head as I do so. In short, I'm an optimiser but I don't consider overpowered (or underpowered, I don't want to be a burden either) to be optimum.
Another thing I value (in my own characters at least) is taking a unique path, or putting a little spin on something. (I love Pathfinder's Archetypes for this reason for example).