I have kept SWIFT but this time opted for V2 let me give a comparison:
-- Swift is costly, in term of price than registration and token tax finally marked difference in fuel consumption.
-- Engine and body specifications both cars are almost same.
-- In acceleration and initial pick Swift is better than V2. Although both cars have very good pick comparing other cars on road.
-- Swift road grip is slightly better than V2. Although both cars have very good road grip in 1300cc category.
-- Interior wise swift is better than V2. V2 have some additional noise in doors etc.
-- (Some tech points) Swift engine uses two coils for firing 4 cylinders which is an older design than V2 using 4 coils for 4 cylinders. So V2 do not heat up spark plugs in Lahore driving conditions where most time of the year temperature is above 30C. This issue is faced in Baleno, Liana etc but not in City, Corolla etc.
-- Suzuki is renowned brand that gives Swift an edge.
-- Suspension .... Swift suspension is hard and not comfortable on rough roads. V2 have very good independent suspension which is soft as well as give better ground clearance.
-- Air bags, Fog lights, Extra support for front bumper, better boot space are some merits of V2
-- V2 comes with 3 year warranty while Swift with 2 year.
I personally preferred V2 over Swift mainly because its economical and without compromising anything on features and safety.