I think the consensus pick for favorite content among most players right now is the colony.
However I'd like to throw my hat and vote in for the progressed storyline with the Tzenkethi. The new mission, Melting Pot, provides a fascinating new angle to the Star Trek Online story, what with light being shed on the WHY behind the Tzenkethi assaults and protomatter bombardments on the planets in the Alpha Quadrant. The fact that we were able to logically reason with one Tzenkethi captain, gain her trust, and team up to tackle a more insidious enemy makes for great plot development. I'm excited by what that means, with a new ally inside the Tzenkethi command structure. Indeed, this is what ST:O has been preaching from day 1, exemplified by the formation of the Alliance previously due to the threat of the Iconians. If we can find a means of bridging the gap with the Tzenkethi, I don't see why they too cannot become an ally in the fight against this latest threat to civilized space.
The other thing I'm excited to see is how this will tie into the future return of the Jem'Hadar and the Dominion. Could this infestation be the latest threat from the Gamma Quadrant? Some other dimension? The future is wide open!
