When I first saw Ishant Sharma, I couldn't help but be impressed. It was not just his hostile spells against Ponting, but the way he got the ball to reverse and proved as much a handful with the old ball as he did with a newer one. He bowled decent pace and generally pretty good areas. Since then his pace has dropped, he's going round the park a bit more, inconsistency in his fledgling career was inevitable, just hope he gets back to where he was.
Broad on the other hand has grown on me, but still think he needs to work out what style of bowler he wants to be, or perhaps what kind of bowler England want him to be. He can look ineffective, leak runs, try too many variations, and then produce a magical spell that will win his side the game. A talent no question, and maintains very good pace throughout, just not his biggest fan and when they have both been at their best, I would edge in Ishant's corner at this stage.