I had a hard time with this. I would like to see a pot with some texture to it, instead of a smooth finish. Also with a mottled coloring that would set off the bark and the flowers. But that said, of all the choices, I picked the blue oval. My other choice would've been the green jade toko. Take a look at the Horst Heinzelreiter pots on this page. Not that you asked....just my 2cents.
There are some that would work really well, depending on size needed.
It's an amazing tree no matter which pot you pick. I'm looking for a light pink flowering ume, with dark bark for a pot I have, so this one is always wonderful to see.