Expansion isn't as powerful as it once was. It's still good for any decently sized empire, since it gives Pop Growth speed (the new meta), +1 planet size and if taken early can help colonizing with a free pop and reduced influence cost on starbases.
Domination feels thoroughly meh. The best you can say about it are the +5% worker output and the +1 Influence... but that alone does not justify taking it. At all.
Prosperity is my go to pick, since +10% mining station income is great (early-game mineral income is mostly space-bound, until you find a mineral-deposit-rich planet), the jobs and housing upgrades on city districts are essential (you ALWAYS use City Districts) and +5% specialist output is actually worth something.
Harmony is slightly above meh, given you never really need to pay attention to amenities, especially not if you already have the bonus clerk jobs from Prosperity, Leader Lifespan is kind of nice though and +5 stability is +2.5% overall ressource production, which is great. More of a later pick.
Supremacy has, still, incredibly powerful militaristic modifiers... which is of course only relevant if you intend to go to war. Otherwise just turtle up and outdo the AI economically and it won't bother DoWing you anyways.
Diplomacy is... there. Federations are still icky and mostly a RP thing. The Federation-replacements for Xenophobes are heavily meh (Bombardment Resistance? Really...). Trade value boosts and lowered market fees are actually sort of nifty. If you're a megacorp, this is a must-pick (3rd at latest), otherwise depends on your playstyle.
Discovery is slightly less 'must take first' because it lost the Anomaly Discovery chance, but it still has two significant early-game modifiers (Anomaly Research Speed and Survey Speed), has the amazing Leader Level Cap +1 & +25 Leader experience gain and a great finisher with the +10% research. Definitely a must pick, the only question is whether you grab Prosperity first.
My order is usually:
- Discovery & Prosperity
- Harmony/Expansion/Diplomacy/Supremacy (depending on playstyle)
- Unity Ambitions
- Domination
Overall, I strongly like the changes, if just because they broke up the meta and made all traditions somewhat relevant to different playstyles.
Except Domination.