Paper maps (OS 1:50K) for me, on the handlebars all the time. That way I can see what I’m near and plan the next 5, 10, 20 miles any time I choose. Always loved following my way on a map. Use a Garmin for recording the route and it or phone if I fear I’m lost, but if I could only take one, it would be the map. Just like old times, though I fear my map reading skill has faded through lake of practice in this gps era.