I think the A-20 Havoc is probably the best ground attack plane in il2. For the following reasons:
1.) It has a decent payload.
2.) It is extremely ROBUST. it can take heaps of damage from AAA etc
3.) It can perform well on a single engine. When an engine goes out just feather it and fly home. Still has adequate performance to gain altitude.
4.)Also, for its size the Havoc is quiet nimble and it is no slouch in the speed department.
Below is a video of a Single A-20 in the ground attack Role. I think it creates an enormous amount of damage.