[colmo]

Axles decide a lot of things - shaft or MOA, worm drive or not? Shaft means you need a transmission, and opens up the possibility of a dig and a lightweight outrunner motor, MOA means you need a 2-motor (and possibly dual esc) setup, likely brushed gear - I wouldn't put outrunners on axles, their rotating can would be too exposed!

A central transmission means you have to be sure the ratios are right - Axial axles on a Losi transmission would fly, for example, whilst the slow worm drive Losi axles and Axial transmission would be geared very low.

Atm, MOA appears to be the way for competition rigs; if this is a fun runner, it doesn't matter.