For that short a run of extra wire, you can probably do either one, just use the same size wire or one size larger.
I can see more problems if the motor leads are long.
Do you mean with equipment placing and wire routing, or something else.
Electrically, unless the ESC is specifically designed for it, longer battery wires are worse than longer motor wires. It's hard to explain if you're not an electrical engineer, but basically longer wires look like inductors in series with the thing on the end of the wires. Motors are already inductive, because they're made with coils of wire inside, so a bit extra
outside doesn't change anything. Batteries
don't natively look like inductors -- with long wires on the battery, when the ESC switches off current to the motor (which it does 10000 times a second) there's a water hammer* effect from the motor wires that tries to force current through the ESC anyway, much to the detriment of the poor thing.
This can be overcome easily by putting capacitors on the inputs to the ESC -- so
read the manual: it should have guidance on how long the battery wires can be before they become a problem.
* Cringe, but if you'e not an EE it's the best explanation.