I do like the A-20, but the Sturmovik is a more reliable plane. It's less susceptible to damage, and pilot wounds are extremely rare.
It also turns on a dime, and with flaps on, it can almost turn with a Wildcat. This scares the hell out of a lot of people in low-alt furballs. If you're good in an Il-2, and you have a good rear gunner, you're gonna bring a lot of kills home. I can't say the same for the A-20, because a good stream of .50's will tear a wing off, whereas said stream of .50's might damage a flap on the Sturmovik.