Strange Liberation is probably the most straight ahead jazz of the three, but that isnt saying much.  Its a very good disc with a great band. 
 
A Thousand Evenings is a very laid back, with an accordion player on every track.  Its a god disc, but its not that jazzy. 
 
Freeak In, wel, the title explains that. 
 
All the discs are adventurous, just in their own way.  I dont have Soul on Soul, but Im guessing it is more like Strange Liberation than the others are. 
 
 
 
 
P.S. I would just buy all 3.