The Ixians and Tliaxu expansion is pretty good, and even if you don’t play with the new factions at all the technology mechanic helps a lot, particularly for the fremen, who I always found need all the help they can get. YMMV of course, but my table loved it. The Ixians really change up the game too with their mobile fortress that counts as a victory point. And having the Tliaxu in a game means that you can barter for the resurrection of leaders early, which is another potential game changer. Pretty neat gameplay interactions.

I technically have the CHOAM/Richese expansion too, but haven’t actually had a chance to play with it yet. The game takes some real time investment to actually play…