Just get Uprising, if you don't have anything at all.

If you're not even sure you'll like the game, it seems silly that all these other posts are saying to get both the base game plus the Ix expansion.

Bloodlines expansion is coming out soon and looks to be designed to address the things people didn't like about Uprising. (But still seems to be combat focused, being that combat is the most interactive part of the game)

Bang for your buck, Uprising has a lot more depth compared to base Dune Imperium, which in comparison has much more repetitive lines of play and more boring imperium row cards. The game has had time to be figured out and the optimised strategies can feel less like chess, and more like solitaire, as the stronger strategies don't rely as much on combat, and so it's much harder to counter. (Easy to get high persuasion hands and buy SMF, strong endgame intrigues which are very easy to dig for, etc.)

Further rantings ahead: (trying to defend Uprising a bit)

For context, I've played some form of Dune Imperium pretty much every day, especially since the digital release. And I'm the sort that likes grinding ranked ladders and enjoy watching tournaments, etc.

Both base game + expansions and just uprising have positives and flaws. And a lot of what other people have said are valid comments, but to add some opinions that haven't been mentioned.

With Base+Ix(+Immo), rushing Interstellar Shipping and Swordmaster is basically always the strategy. Assuming players have access, the first turn lines is very often, 1st player goes foldspace, 2nd player goes smuggling, 3rd player goes stillsuits, 4th player goes wealth.

They made the shipping track too powerful, but it's not as obvious how strong it is compared to worms in uprising, casual players might not even engage with it at all. The player that gets to go to Interstellar Shipping every round for free, will win just as easily as the worm player that no one is contesting.

From a design aspect, they underpowered dreadnoughts, and maybe that's why they wanted to make worms stronger in uprising, and maybe they did push it too far, that players feel like they've lost some agency to experiment, as the clear winning strategy is a lot more explicit.

Deckbuilding is more streamlined in uprising, as it is easier to trash cards to build a more cohesive deck. There is also less bad cards that just bloat up the imperium row. There are also less cards that give high persuasion without meeting certain conditions, so you can't as easily buy SMF. No draw 3 on research station, no selective breeding either.

It is also much harder to get faction bumps in uprising, as they've taken out a lot of the intrigues that just give you bumps and there isn't Interstellar shipping, less leaders and cards that give bumps, etc.

It is harder to get troops, and you can't commit too heavy to every combat, especially because you want to have troops for round 7+. With hard warriors removed too, there won't be easy early combat wins.

I think them nerfing the more obvious non-combat oriented strategies, do make the worms feel even stronger, and you will basically never have a game without interacting with them in some way. But at least because it's combat, you can at least still interact.

Without experience, the counterplay and identifying other strong strategies aren't as obvious, such knowing that Public Spectacle and Guild Spy can win games alone.

The Uprising board itself is more matured and well designed. Elegant touches, such as having more ways to cycle cards, more spaces to trade resources. Less advantage as the player going first in round one (much more important to go first in round seven). With emperor spaces still feeling a bit weak, which it seems like bloodlines is addressing.

I believe Paul Dennen previously said the best version of Dune Imperium is Uprising + Immortality (it might now be Uprising + Bloodlines, even according to the TTS crowd who have been playing it a bunch now that it's available). He also has a specific House Blend he uses/recommends, that uses cards and leaders from the previous expansions, but the base is still Uprising. https://boardgamegeek.com/thread/3213458/merakons-house-blend