If you are looking for a best 150cc segment bike in both performance & mileage, then Yamaha fz s v2.0 should be your ideal choice.
Yamaha which always tops in build quality, better performance & efficiency, has played a game changer in 150cc segment by introducing fz s.
I have been using the bike for 6 months, I havent faced any issues till now. The fuel efficiency is also commendable, which provides 40-45 kmpl ( City) & 50kmpl ( Highway).