@kvbcycles - I recommend the Garmin 520 and above if it wasn't for the fact that garmin.com has been down for a week (due to ransomware attack I believe). I have started using my old (4-years+) 520 for navigation recently and it is doing a good job for turn-by-turn navigation.
Like you, I am a big fan of ridewithgps for route planning, it is easy to use and platform-independent. I must take a look at OSMand too. In my bookmarks I now have (with marks out of 5): I also have a Garmin XT for motorcycling - which I am in two minds about.
Google maps 5/5 - keeps getting better
Bing Maps 4/5 - free OS maps for UK
Google My Maps 3/5 - POIs plotted over GPX routes is useful (accommodation, campsites, cafes) - see
https://www.google.com/maps/d/edit?mid=1w_99dhNkgjuy_vRZKJQ7A7o-QoU&usp=sharing for my NSCR route, now overlayed with photos geotagged to the route
ViewRanger 4/5 - long distance walking essential
Strava - 4/5 - I avoided this for ages but lockdown has made it an addictive app
RidewithGPS - 5/5 - best route planner IMO
Rever - haven't explored this yet - m/cycle oriented
MyRoute - 4/5 - good route planner for m/cycles with TomTom or Garmin, nice community
Garmin Connect - 1/5 - down for a week now :-( - clunky
Garmin Explore - 1/5 - hopeless app - no wonder Garmin IT is so weak - don;t even get me started about Basecamp. Garmin are like Nokia - will soon be hardware only
cycle.travel - x/5 - yet to use this, but came recommended
searchforsites.co.uk - 4/5 - excellent campsite finder for campervans and cyclists
So many options to choose from. Maybe I'll just go back to paper maps and compass - it's easier and more engaging.
"GPS will take you where you want to go; a map will take you somewhere new"