BBR is better than nothing, but it's good to be aware of its weaknesses - people have uploaded all kinds of routes they've done, whether they were any good or not. To get the best out of BBR, you need to look beyond the map, and go click on each road you're interested in and read what the person said. Too often it's something like "lot of boring straights but it got me to my Mum's in time for lunch". The Bikers' Britain books are excellent - I've never followed one of their routes and been disappointed. There are some apps like kurviger that will find twisty routes for you, but to me there are a lot of ingredients to a good road - sight lines, traffic, road surface - as well as bends', and I've not found the apps to be a replacement for local knowledge.