I've used Backcountry Navigator for quite some time, and find it to be very good. I've also paid for the Accuterra maps --- optional, not needed, but when I hiked half of the Florida Trail in January, the Accuterra maps often had the FT on the base map, and it's something like $20 a year for an additional map source.

Hiking in Spain for the last month or so, I found it very handy --- a couple of different map source options worked there and I could find a very accurate trail plot. This helped in particular as my little group typically started hiking well before sunrise each morning, and the app was a big help at times in low light situations, just to keep us on track.

BCN has a bit of a learning curve, so I don't suggest buying this and then trying to figure it out on-trail at a time when you need it. Play with it a lot on very local trails and around home until you've got a good feel for what it will do for you --- and how to do those things. But I'm a fan. I like the way it's supported too.