Well, MMOs decisively win for me although it is tricky if I work in opportunity costs. EQ and even WoW were hundreds (or, fuck me, thousands) of hours of play for relatively little cost. Still, I did occasionally skip money-making opportunities back in the EQ days so that should count against!
Modern stuff? Most games to be honest. Almost anything I play for more than ten hours is much, much cheaper than other entertainment I'd spend my time on.
Specific nods to Dark/Demon Soulses, most FFs, Borderlands I/II, all the RTSes ever, CivIV, the HLs, M:TG and Plants v Zombies.