The Apocalypse DLC is lots of fun for building bigger ships like Titans and Colossus (Colossi?). There's nothing quite like the disturbing act of clicking on a planet you're about to destroy and seeing the population, the diverse species who call that planet their home. And then you wipe it out in an instant with your world cracker. Somewhere across the galaxy, Obi-wan Kenobi is beside himself at your own monstrosity.
But even more fun than that for me is the Great Khan. It's always fun to have some surprise disruption to the status quo in the middle of your game, and a great ravaging horde of space pirates add to the color of the moment. Defeating the Great Khan feels like vanquishing a mob kingpin, and I couldn't help but pump my fist as I watched his flagship explode.
People play Stellaris for different reasons, but one of my reasons is the flavorful event texts, whether anomalies, science projects, or the random Worm in Waiting who happens to appear. So Distant Stars was a no-brainer for me because it adds more of the best part of the game.
The Ancient Relics DLC is... fun? It's a good new game mechanic of discovering powerful artifacts that provide empire-wide bonuses, and I like the archaeology process, especially the stories at the dig sites. But overall it felt like there weren't enough relics? Or at least I wasn't able to capture as many as I'd like. If another empire gets a relic before you do, there's no way to capture it. If you conquer them, the relic vanishes from the game, which is disappointing. Hopefully they'll address that, because I do like the idea behind the relics DLC, but I'm not sure if the DLC is worth it as is.
MegaCorp is great when you want to be play the ruthless capitalist empire slowly draining the galaxy of its wealth. And city-planets are awesome to behold!
It's not perfect though. Despite the spirit of the DLC, there's still no way to take over the galaxy without warfare. The next DLC, Federations, might address this by boosting how powerful a MegaCorp can be in terms of taking over their neighbors, but right now it's not there. Also, playing a crime syndicate should be lots of fun, but it's relatively easy to eliminate crime on planets, and so it's difficult for a syndicate to make much impact.
This is a fun game, but there is a glitch when you have to smack the scarecrow with a bat. It locks up, and you have to force quit or reboot. When you do, it will take you to the scene where you have defeated the scarecrow, and you can continue on with the game. At least this is what happens on my computer (every time). So my advice: skip defeating the scarecrow.