My personal assessment of the 3 cars...
B44.1 = Easy to drive, simple build, little setup work needed, US designed.
Durango = Aggressive to drive, well engineered, more work to setup, European designed.
SX3 = Never driven one, more complex to build (partly due to belt transmission), looks more complex on setup (but with the right guys around to advise it'd probably be ok), UK designed.
All 3 have good parts availability so would score evenly on that...unless you have a track side shop that only stocks a particular brand(s)!
Of the 3 the SX3 is the only one I've not had any direct ownership experience of...but our club has all 3 running, so see them all regularly.
They are all as quick as each other really...but do feel different to drive, so pick the one that suits you! They all appear in A finals at the biggest competitions on all types of track, so it is a bit of personal preference tbh!
I own the B44.1, it suits me very nicely
