Having used both, I much prefer neither: I use
https://cycle.travel/ which is run by a keen cycle tourist, who is also a cartologist by day.
The strap line is, "Life is too short to ride bad roads".
I've used Komoot, ridewithgps, and Strava. I found their routes were always compromised in different ways, so would work through them painstakingly to remove the obvious mud lanes, awful main roads, or strange convoluted Town bisections.
It's free to use with some extra features for not much money. I pay £2.99/month to get the ordnance survey maps.
Cycle.travel had the street view feature years before komoot. I also like the geograph feature - which on byways usually has a picture somebody has taken so I can see how muddy it might be, or not.
He really sweats the details about road surface, and folds in traffic data to find the lanes with lowest traffic. That traffic data is probably his magic sauce for building really nice routes, that seldom need tweaking.
cycle.travel is the only app I frequently route, then go. It throws up the least number of, "Why did you pick this?", objections.
I'm in danger of being a fanbois - but it's not that well known, and I consider it head and shoulders above the others for routes with nice lanes.