i don’t categorically suggest one is better than the other, they share many similarities as noted.
there’s been several detailed explanations above that go into those differences and their potential meaning or contribution to using them.
if i had my preference ive been most happy with full hydraulic on past bikes,
myncurrent ebikes are folders so came with mechanical cable activated discs, the sense of feeling throug. the levels is in my impression much diminished over how full hydro felt and the level of fine control full hydromfelt it delivered.
a future upgrade when i wear out these brakes could be cable + hydro calipers. i’ve yet to experience this combo but because my bike is a folder i don’t think full hydro is practical or even possible for me, i’d have to research it some more.
my personal, main benefits for hydro (full or presumably only hydro calipers) is simply having both braking surfaces move equality against the disc plate, tends to result in more predictable and quieter braking operations. for me has nothing to do with stopping power, whatever that even is beyond a human impression.
the vast majority of braking i find myself doing on the ebike is feathering to modulate low speeds in precise ways that make the bike feel most nimble, adept, and controllable…. think navigating around intersections, multi-use trail heads and street crossing where they have bollards, gates, mazes to keep cars and motorcycles out… these are all areas where total,stopping power is less needed for me and ability to modulate betwen say 2.3 and 2.5 mph to navigate and steer without having to walk the bike…. i’m always slowing when passing people on certain trails, being cautious and responsible but most of that is not about braking distance or stopping power and on other bikes, hydraulic systems seems to have faster response and more precise response…. not a scientific measurement, just how one person feels having used both mechanical discs and full hydro (i have not use cable + hydro calipers yet)
majority of my use is paved and packed gravel trails, not off-road and not on road, i’m not a commuter. so my needs and experiences could be quite different from others.