prunus incisa

Hi, I am getting a a very japanese quince and also a japanese cherry blossom "oshidori" and I have read somewhere that these plants should be repotted in the autumn. I am not really chasing flowers next year, I want them to grow well and get established and also avoid diseases that usually...

So I got this prunus from a nursery, did the initial general prune and a bit of wiring and now I'm a bit unsure about what front to select and after that is done wich branches to cut next. My decision is between: a)b) I think in b) we can see the main trunk bend backwards, but in a) I think...

I'd like your thoughts and tips on how to improve the general shape of this young tree. What would you cut, leave grow, shorten, etc... Thank you! :-)