Here are my observations:
Liva:
+No hatchback can match back seat comfort
+ Space
+ Toyoto unmatched reliability
- Too thin metal sheet (Really too bad)
- Unrefined engine, i felt too much noise inside cabin
- Boring design,awful interiors( i have that glove box design)
Grand
+ Features features and features
+ Perfect city car just drive like any other petrol car
+ dash intergrated gear lever and excellent interiors
+ new bee
- Lack punch on highways defenetly not under powered
- Hyndai maintenance cost comparing to toyoto, i paid 3200 for second(free) service.
- back seat is not an perfect 3 seater.
My recommendation is if you are too much spoiled with Tata vista (especially back seat comfort Liva is way to go dont even think of Grand i10
But if you are ready to comprise on Backseat comfort do a test drive and decide yourself (my personal recommendation is Grand i10 to escape yourself from Taxi image)