What is the best commercial you've seen in the last few months and why do you believe that it's effective?

Not one in particular; quite a few of them.

The best TV commercial I have seen in the last few months is that of Surf Excel- Daag Acche Hai(Dirt is good for clothes)....
Never before has a detergent ad been so refreshingly cute.
The Daag Achche Hain series by Surf Excel is a pleasure to watch on TV even between the most-engaging movies.
Among the ads that were part of the series, our favourite is the one that shows brother-sister bonding.
Watching a little boy ‘beat up’ a puddle to please his younger sister because she fell into it and getting dirty himself in the ‘brawl’ was a delight.
It made us all wish for a brother like that too.
So yes, ‘daag achche hain.’