Okay, Well as far as HTC One S is concerned , I have read that this one is not same as the one being SOLD in USA. The Indian version of One S doens't have the "Krait" architecture.
Also , SII is a legendary phone but doesn't deserves to be in Sub 20k category , because of the competition it faces.
Have gone through Sony Experia SL , considering if he's ready to increaze the budget a little bit.
O/W , I will ask him to go with LG L9 saving some bucks instead. IMO too , its the best in 20k category and beats a few Sub 20k models as well.
Only issues seems to be the inferior camera , but we'll see.