Komoot is my app of choice. I bought the full world map coverage a couple of years ago, and its largely been flawless.
Routing in the UK is sometimes a bit dodgy as it doesn't understand rights of way per se, but you can easily cross-ref with OS maps. Also, being OpenStreetMap-based, you can correct and edit the mapping yourself.
I used it on a two-week ride in France in 2018 and it was great - I had to fall back to the 3lbs of paper maps I was carrying only once as I needed to see more area in one go. I had a Xiaomi Redmi Note 4 (now have a Redmi 6) in a rugged case with a medium-sized power bank, all inside an A5 Ortleib waterproof case, with a correx board zip-tied to the bars.