Used JDM Suzuki Wagon R market ki Gari Hai, spare parts may be easily available. On the other hand, you may find difficulty in finding spare parts for Nissan Dayz Highway Star.
But Yes, parts for regular preventive / periodic maintenance are easily available for both of these in the markets (filters, brake pads, etc.)
Market value of Wagon R is also better than Nissan Dayz.
Engine, performance and milage of both vehicles will be almost same, however, features may be comparatively better in Wagon R Stingray.
In my opinion, go for Suzuki Wagon R Stingray!