It depends on what your focus is for your gunners.
If you have end game in mind ( lvl 90+), the weight you can reduce a gunner by and repair rate a gunner provides is the only thing that is different between various gunner setups. Accuracy and reload are the same for all, they have long since capped.
Elite reload you can make the lightest, the elite repair gunner gives the best repair rate while being the heaviest gunner ( but only slightly heavier than the elite reload).

Other gunners come in to play only if you don't want to spend olives on buying elites, or have concerns about playing them at lower level.