It's debatable question
If you follow Pak Suzuki manual which says 10w40. Then 5w40 is best
If you follow international Suzuki manual which says 10w30 or 0w20 then 5w30 seems to be best option .
But IMO 5w40 is year round oil and good one for Swift.
You may get few KMS extra with 5w30 but it will not perform in term of engine protection as good as 5w40 when engine is.hot.