Cultus looks better, have better fuel economy (K-Next K10B engine) and resale. Seating position is better than WagonR. On downside Cultus body is very weak, starting to rust in first 1-2 years. Most of cultus owner reported low A/C cooling. and Dashboard quality is plain plastic
WagonR have more cabin space, tall doors make it easy to enter and exit the vehicle, driving view is commanding and excellent A/C. Looks are very plain and unattractive, Build quality is slightly better than Cultus, both interior and exterior.
Cultus look more proper hatchback family car from looks.