Refill port design: top-fill vs side-fill

Top-fill and side-fill designs can both work well, but the difference shows up in the routine. I pay attention to access, whether the device needs to be removed from a case, how easy the seal is to inspect, and whether the fill area collects residue.

What makes one design noticeably better for you in daily use?

Top-fill when it is genuinely accessible. A hidden top-fill that still requires awkward disassembly defeats the point.

Side-fill is fine if the plug sits flush. I have had a few where the tab catches on things in a pocket.

That is exactly the distinction I would keep in a review: location is one fact; the actual refill workflow is the useful observation.