Buddy u have asked one of the most hardest question
The only answer to it is to Test Drive both of them and buy the one which Satisfies you.
and about efficiency & resale Vitz takes the lead in it.. if properly maintained/tuned it can give you minus or plus 15km/l in city..
But in my opinion both cars are Totally Different !!
Vitz is Automatic whereas Swift being Manual
Vitz is 1.0L Producing 67hp whereas Swift being 1.3l producing 92hp
Built quality of vitz is better as compared to swift
Vitz has alot more options as compared to swift
And there are 2 Trims of Swift DX & DLX
DX is just a basic version and i will not recommend it to you as it does not have ABS and many other standard features.
DLX is fully loaded version of swift in which u get ABS, 4 Speakers, Alloy Rims, Fog Lights, 2din CD player, keyless entry & Body colored Door handles & side mirrors (DX variant have none of these features so it doesn't worth it)
Whereas if you buy vitz even its basic variant have got ABS, 2 Airbags, Keyless entry, dvd player or 2 din cd player and many other features like body colored side mirrors and door handles...
and the fully loaded version of Vitz is packed with Push Start button, Smart Entry, Indash CD Player, 8 Airbags, Alloy rims, Fog lights, RPM meter and some more features...
Vitz has got all the luxury & safety features and also drives smoothly and its also quick but not as quick as a Swift.
Swift has got all the Basic features which a car should have these days and is very fast even faster then a Corolla 1.3L
My advice is to Test Drive both cars and buy the one which u like