As fair warning, GURPS does have a habit of getting very complicated very quickly. It's deliberately designed to basically be able to do everything, and if you know how to use it it works just as well as any other PnP RPG, but it's very easy to get carried away and end up with half an hour's paperwork required for a character to walk across a road.
And that is why I've almost never been able to get anyone to play it! They take one look at the rules and think the session will implode under the combined weight of modifiers and skill-defaults. The same basic principles of difficulty-checks apply to every PnP game, you just need a GM who knows how to play as fast and loose as required. And since GURPS can assign a quick 3D6-check value to any conceivable situation, it's a great system for playing fast and loose.
Not to mention there's at least one rulebook designed for every setting and licensed property you can imagine. (Of course, most are designed for early 3rd edition and long out of print, but still.)
The thing is, the GURPS RAW is
incredibly dense, and GM's playing fast and loose with the rules is, to most PnP gamers,
even more terrifying than the dense rules. Many gamers have
nightmares about the GM playing fast and loose with the rules. The fact that in order to run a GURPS session in any reasonable timeframe pretty much
requires the GM to do this is enough to cause mass hysteria at the merest whiff that someone is thinking that they might possibly mention it in passing.
Personally, i prefer Savage Worlds over GURPS, like GURPS the ruleset can easily fit pretty much any setting and it has rulebooks for lots of the more common ones as well as some SW unique books for some rather interesting settings indeed. Unlike GURPS it's deliberately designed to be incredibly fast, efficient and streamlined, and i'm yet to find a system that's more streamlined without losing functionality.
Ultimately with PnP RPG systems though, it's each to his own.
Paranoia is also
hilarious fun if you have players who understand the point behind the system.