Tuesdays: Pathfinder second edition. Good system, but also quite heavy. We're into our second campaign, Stolen Fate, having finished Abomination Vaults.
Thursdays: Lancer. Great mech-rpg. It should appeal to people who like mechs and who feel D&D is too mechanically bloated and not tactical enough. The most unusual thing about it is the near total separation between the narrative system and the tactical combat system.
More of a hypothetical, but I would like to run Triangle Agency. It's basically, well, uh... Difficult to explain. It's like Paranoia + X-files? The rulebook is absolutely insane.