I like Vinay, simply because he's toiled away for years in Ranji. Plus he plays for Karnataka and almost helped win them a title against bloody Mumbai.
He deserves his test spot because of his FC achievements, but its pretty clear he's a run below Praveen. I've seen Praveen swing the ball both ways in non-swing friendly conditions, something Vinay can't do.
I also get the feeling Praveen is just a smarter bowler in general.