Derbi 150 will be pretty easy to maintain. Better buy cbf 150 as its Honda brand and will have far better spares availability compared to Derbi.
Kpr is proper brand and if budgets isn't an issue then it's best choice not tension for first few years. It being water cooled and efi will pose some challenges to normal hathora mechanics but both technologies are old. Efi in cars etc. Even mehran has it.
And even Rickshaws have been water cooled for past many years and are plying on roads using momin oil. And still rock solid.
If I were you and was in limited budget I would have bought cbf of no budget constraints then kpr..