Hi, my mainstay most-used plane is a Stanley No 4 type 18. It's really true and works great.
I've used a No4 type 15 and type 19, and I can't really tell much difference between any of them once they're setup nicely and use the same Hock blade. The 19 seemed to have rougher casting overall, but still worked well.
Was wondering if any of the early types would be better for woodworking use or are they all somewhat the same?