We are currently playing 2 campaigns, Wild Talents and Eclipse Phase. However, it doesn't hurt to think about the next one.
Some ideas:
Iron Heroes: Swords and sorcery fantasy - all PCs are badasses without the aid of magic - they are defined by their fighting styles and the choices they make. No magic item shopping or accumulating wealth beyond measure - spend the gold as soon as you get it on wine, women and song.
War Torn modern/near future GURPS: Players are normal humans with some unusual skills or experience in a society torn apart by civil war. They can raise an army and make themselves warlords, make a fortune in the underworld through black market smuggling or save thousands of lives by protecting refugees. Of course, this assumes you're willing to take the risks and survive.
Zombie post-apocalyptic modern/near future in GURPS or Nemesis:
Rebuild society or take down the corrupt bandits and petty warlords? Find the cause of the undead or engineer a cure? Become an intelligent undead and fight against bestial instincts?
Yakuza GURPS: In the chaos after World War 2, a group of small time hoods are given a chance to start a Yakuza crime family. Will they focus on expanding their hold in the black markets or work for the CIA against communist agents? Fight in underground martial arts tournaments for honor and cash? Work for the police as an undercover informer to bring down the other families?
Rogue Trader: Evil capitalist colonial exploitation Star Trek