[nindalf]

I can't speak for others, but me personally - it doesn't matter when it comes to the interface. I'm cool with En_IN, En_GB and En_US. Whatever the default is, I let that be. I read so much user generated content (like this thread!) where I can't control the locale, so I have to be cool with it.

I'm more particular about the input, especially if it's auto-correcting. I prefer "analyse" to "analyze" and other similar changes so I set the software keyboard accordingly. En_GB and En_IN would both be fine, except for the currency symbols. I prefer En_IN because it gives me access to the Rupee symbol (₹).