I know 6 Standard Poodles - 4 are dog aggressive. I've seen
others write that Standards seem to be more dog aggressive than
Miniatures and Toys. This is just anecdotal, of course, and my
sample size is small.


I don't know if I'd say Standards are *more* aggressive. My experience is
that a LOT of Standards are serious bullies, but I don't think that's all
that different from the smaller versions; I just think it's more serious in
a larger dog.
Problem is that too many owners of ALL sizes of Poodle let them rule the
roost; what's merely obnoxious or annoying in a 15-lb dog gets a lot more
serious when the dog weighs 60 lb.

I will also say that IME, the smaller the Poodle, the more likely the dog
is to be highstrung and nervous; that may be a function of how they're
raised rather than something intrinsic, though.