The folks over at GamePointsNow have successfully leaked the monthly PS+ offerings the past few months, and they're back with another leak, this time for the PS+ offerings for the EU PS store.
The games being made available for PS+ come next month will be:
PS4: Mercenary Kings
PS3: PES 2014, Sly Cooper Thieves in Time
Vita: Hotline Miami, Moto GP13
Thanks to NeoSpoon for the tip.