Maps you can actually read

Ordnance Survey's own mapping, which is the reason it leads: a proper topographic sheet is dense with detail that only resolves at a decent size. Reading contours through a phone-sized window is the single clearest example on this site of a document being bigger than its screen.

Route planning for riding, hiking and running, built around routes other people have already done. Planning is a map-and-list job — the profile of a route beside the ground it crosses — and it is the half of the app that has never fitted.

Topographic layers, weather and navigation for back-country use, with the layers being the distinctive part. Comparing two layers over the same ground is a thing you do by looking, and looking requires something to look at.

A walking map with drawn routes and elevation profiles, deliberately small and sharp rather than a platform. An elevation profile is a wide, short graph — the exact shape that a phone screen in portrait handles worst.

The default, and the one with the most detail attached to each point on the map: places, photographs, reviews, transit. All of that detail arrives as a panel over the map, which is the arrangement a second pane exists to fix.

A flight tracker with an honest use for each size. The gate, the delay and the countdown are a glance at a closed phone; the map, the timeline and the aircraft's day are a sit-down. Few apps split that cleanly.

Live air traffic over a map, which is the category's showpiece. The whole appeal is a crowded sky and the ability to pick one aircraft out of it, and a crowded sky through a small window is just crowded.

The same idea with a different presentation and a long history of doing it. On the list because having two of these is useful — coverage and detail differ — and because a second screen is what makes the comparison practical.

Itineraries assembled from confirmation emails into one timeline. A trip is a list of times and places, and a list is what a phone does well — which is why this sits low. It gains when the itinerary and the map of the day can be seen together.

Planning and booking, with the reviews that make it a reference as much as a shop. Last because the gain is browsing rather than navigating: more results visible at once, which is the same argument as any catalogue.