The best saddle will be one that fits your horse and yourself - unfortunately there is no other answer that can be given based on what you have posted. Are you familiar with proper saddle fitting?
The choice between western and Aussie is really a matter of preference.
I'm in the same boat you are, I have a 1500lb Friesian/Perch cross. I have a Duett English saddle, but I want a western style for trail riding him. I'm only 5'2". I have my eye on an Aussie, nice deep seat/thigh blocks and I like the English style girth and stirrup leathers. Most western leathers don't adjust for my short legs. I really want a Tucker, but I don't think they make one wide enough for my horse. I'll keep checking here to see what answers you get.