Smaller chibi sprites (like VX/ACE or MV's) are great when characters don't have a lot of small details, because then you can really exaggerate the details that are there. The larger heads give a lot of room for expressions/variations in face style, although the head-to-body ratio makes them a bit of a pain for posing/animating. I generally like the chibi styles for RMMV and VX/ACE, although I'm not a fan of how the eyes look on MV's. They're a bit nightmarish.
Mack sprites, though I'm not personally a fan of the style, are really nice when you have more detailed character designs. You have the space to draw out clothing/hairstyles without having to squeeze in or omit details, have slightly more realistic body proportions to make animating easier, and still maintain the larger head size to add expressions. It's a weird complaint, but the issue I have with Mack sprites is that they have the larger body size everywhere else, but don't have any sort of neck. I think they look fine when the characters have a scarf or hood, but the head-shoulder area on sprites without them looks super awkward to me.
I don't really have a preference between the two styles when I'm playing a game, but from a spriting perspective, chibis are much easier to handle when you're making everything from scratch lol.