For those saying they wish Raptr was still about to track their games. There is a new alternative in HowLongToBeat.
It's all manual tracking so for those who just can't be arsed with that, that's fair enough. But it's the only modern alternative I've found to Raptr that tracks your game hours and such nowadays.
As for my most played. League of Legends, Halo 2, MH4U and R6 Siege are definitely up there. I also spent a lot of time playing Mercs V Spies in Splinter Cell: Pandora Tomorrow back in the day.
Fallout 4, AC Odyssey and RDR2 are all close to 100 hours in the SP department for me. Persona 5 was 92 hours, Xenoblade Chronicles 2 was 95 hours.
Lots of the early Forza games I must've spent a ridiculous amount of hours on too, probably Forza 1 and 2 were the most.