Brio
Pros:
Compact than WagonR.
Airier cabin thanks to the large windows. ( This also makes one feel that brio has much more space than the WagonR)
Honda badging itself suggest that its a high revving peppy engine.( especially good for driving enthusiasts) . The WagonR though has a smooth engine and gearbox cannot simple match the brio in terms of excitement and driving pleasure.
Cons:
Dashboard design is unconventional and this can be a let down for many.
Less fuel efficient than the WagonR.
High on maintenance ( since service and spares are costly) . Maruti Suzuki on the other hand provides the best service in India.
No diesel or CNG option. ( WagonR has the duo version that appeals to some)