GURPS – There are no artificial limits based in class or level; if you have the character points and GM approval, you can buy any skill or ability. There is no one setting, allowing a GM similar freedom when creating a campaign. Yet, despite all that freedom, there are still enough rules for it to be a gaming system rather than just “Theatre of the Mind”. And the worldbooks they have for less creative GMs are extremely rich and detailed, as are their other sourcebooks; they *really do their research! High-tech, for instance, focuses on gear and weapons from Tech Levels 5–8, analogous to our own world from about 1850–2013, and will teach you enough about the history of firearms to come across as a know-it-all at gun shows while Biotech gives a crash course in genetics—(including history, like Mendellian heredity)—that you can’t help but be educated as well as entertained by how detailed Steve Jackson Games made GURPS.
Shadowrun – Only one setting, but a very rich and detailed one. It’s a mix of cyberpunk and fantasy, and gets into the complications of having mages,cyborgs, and trolls in the world. Racism takes on new meaning; who cares that you’re black when that guy across the room is 9’4”, 800 pounds, and has a horn in his forehead? Megacorps are the effective law of the land, there’s always people willing to pay handsomely for dirty deeds done by deniable assets, and often doublecrosses as those employers sometimes seek ultimate deniability by eliminating all witnesses.
Both are detailed, neither have classes or levels.