What's your planned usage? I looked at the 445 and 455 before I got my BX - and am glad I finally went with the BX. A major reason for me was that the local JD dealer was super-arrogant. But, aside from that, the usefulness of the cat 1 hitch, the 4wd and the general beefiness of the BX swayed me.
It all depends on your usage though - the 445 and 455 are fine garden tractors - a couple of the local lawn-mowing services use them (not yet switched to ZTRs!!). It's just that JD's pricing is so high that they are forced to compete with the BX.
Having said all that, my Kubota dealer tells me that the primary reason he hears for switching to the BX is the 4wd. Mowing hills and plowing snow appear to be the reasoning locally (SE PA).
Hope this helps - I'd be interested to hear your planned usage.
Best of luck with the decision.