Host dragon is delightfully gross, and I am absolutely going to use it against my players at some point (Letting me say the sentence "alright, so the dragon's going to use its Covered in Bugs reaction" is pretty great - genuinely impressed at how evocative the names for abilities are in this book!).
I was a little surprised that the abysium is an arcane dragon, because MC1 was talking up "skymetal dragon" in a way that made me think that was a primal-only category, but I really do like the Cartoon Radiation Dragon, and it's ability to mess with what damage types it deals is a fun trick. Also like the ability to supercharge it's breath weapon - I'm picturing some Monster Hunter-esque chargeup animation there.
Akashics are also fun - the ability to "eat" knowledge about a creature by biting them is a fun trick, and their RK-focused toolkit is both thematic and makes a fight with them feel unusual. Also, they look like a Metroid boss, and I mean that as a sincere compliment.
Honestly I like all of the new dragons (Cosmic Dragon, you are literally a giant lizard Solarian and I love that), and I really really hope we get some Space Dragonblooded rules in Galactic Ancestries!