OsmAnd - tried this on 3 devices, none could download/render anything at all on any network connected. Looks like a heavy thing anyway
It packs this much functionality in one place, all available offline. Once you get past the counterintuitive UI, you start to like it.
It covers public transport, opening hours, all kinds of PoIs, distance measurement tools, hill shading, contour maps and customizable map views, being able to measure routes in advance (calculate route from any point x to y).
try "maps" for something more basic (white logo with black M). it's a fork of mapbox's "map.me" app just without any ads