Quick search of midi file and playback:
1)SD1
2)9000Pro
3)VA7
4)PA80
However, even though I've ranked them in what I think is the fastest to slowest, the difference between all 4 of these is very small. They are all very good for speed.
In sounds,
1)SD1
2)VA7
3)PA80
4)9000Pro
Again, the difference is very slight between the 4.
In other catagories, such as style, user friendliness, effects, etc. the orders would also change, but I'm only evaluating what you have asked for.
George Kaye
Kaye's Music Scene
Reseda, California