I didn't know there were 3 more Azules! Which would you recommend getting after the original? Wikipedia mentions Stained Glass of Sintra, Summer Pavilion and Queen's Garden.
In my opinion the rules increase in complexity in order of release, with Queen's Garden being by far the most complex. Depending on how much complexity you like, it's a linear scale in my opinion. All four are fun and they are soon to release a special edition of the first game that is chocolate themed.