Welcome aboard Safa4w, Glad to have you with us. I noted tonight that so far there had been no response to your question.
I saw your question the night it was posted, But I have to humbly plead total ignorance. Here in the U.S. They have chosen not to allow us any diesel versions of our beloved swift.

. (Although I think they would sell if the price came in at 20k or less) So if everyone else is like me. they chose to defer to someone else that has firsthand Knowledge.
But as my wife would tell you, That has never stopped me from rendering an opinion.

. Although my prejudices are to the swift, I would recommend.1) Purchasing whatever brand and model that has the greatest parts support,(Meaning ease of locating spares),2) Pick the one that has the longest history of availability,reliability and longevity in your country. 3) Ask the Guys who will end up working on the car when it does break, which they recommend. Lastly Never be the 1st guy on your block to try some(any) manufacturers new technology out. (That is a recipe for continuous "Open Wallet Syndrome"

)
I would also recommend the stick shift instead of automatic. for mileage reasons(3-8 MPG in most cases) and I have found that the automatic equipped diesels seldom have the power to get out of they're own way due to the shortage of gears (3-4 instead of 5-6) I'm sure some of my more tech savvy friends could cite exceptions to me general guidelines, But they are just that, general guidelines.
Let us Know what you end up getting, And personally, I'd love to see a picture of the diesel swift, and its stats, price , mileage figures etc. Best wishes ,Jonathan