Stellaris III: Shop at the Paradox Megacorp!

[Olinser]

Which DLC are worth getting?

In general, Synthetic Dawn and Megacorps are the most 'worth' getting because they actually add playstyles to the game. Megacorporations and Machine Empires actually play differently from standard empires, and add the most to the game. But if you don't actually want to PLAY those empires they add nothing and can be skipped.

The rest are just niche stuff that add small stuff to the game that will show up but doesn't matter that much. Distant Stars probably adds the most just because of the chance to get the Nanite world colonizations that gives you 16 free worlds in the cluster.