I cant see how there can be one type of ultimate engine there are so many!
And you cant compare a 4 cyl yb to a 6 cyl Toyota engine!
I think for a 4cyl engine that's quite old now the yb dose very very well and still holds its own with 650bhp being an easy tune! and for an old engine there still used today at the top level of rally cross so cant be that bad really!
But I guess the ultimate type of engine has to be a v8 for out and out power you just have to look at and hear a drag car or see one go!