Playing through it slowly but the first Retaking Theves mission is my favourite so far for the sheer chaos. The radar is just a wave of LOL RAILGUN INCOMING, your improvised landing forces are screaming, and the orchestral piece gives it a sense of exhilaration that made AC7's early missions with Mihaly and the ADFX-01 drone so damn satisfying. The first land battleship showdown also for the hilarity of it, especially when you can tell the writers and designers for them were aping off of Homeworld: Deserts of Kharak in terms of aesthetics and functionality.
Plus for beautiful meme mashups like this:
https://youtube.com/watch?v=FqzCQ9cm4mg
I love these things, it's like someone took the P-1000 Ratte and thought "yeah it's utterly retarded - but what if we hand wove away reality?" There's something immensely satisfying about seeing hundreds of thousands of tons worth of guns, metal, and men ride around on tracks without a care in the world. Sotoa: still need to liquidate 'em, but no denying they're living the dream.