I know of 4 types of Datura.

Datura Stramonium
Datura Inoxia
Datura Metel
Datura Weightii

All the above I have seen in pictures..

Also 1 that I have seen a drawing of called Datura Ceratocaula.

There is no "best" strain of Datura each of them IMO are just as powerfull as each other.

I really hope you have read alot about it, and even if you have I would advise against taking it.

Here is erowids report on it.
http://www.erowid.org/plants/datura/datura.shtml
Mogizzle Reviewed by Mogizzle on . Datura ok any of u guys know which strain of datura is the best? Rating: 5