Raiju is my jam, i like the feel it gives. But maybe its because its familiar to me as its rather similar to DCSS's (looks a lot less like a scared cat tho
)
Then again, with a beast such as that, its hard to go wrong!
Another cool demon is Kisune
>.>
Thats unlikely to go wrong too
And while i don't know if it counts, West is pretty cool looking too!