I've not used Avanza but have really liked Offroad Atlas. It was only a buck when I got it and allows you to download unlimited MVUMs. The developer is great to work with and answers email in a few hours if you have any questions.
https://offroadatlas.org/
As some of you know... I have a bit of a sore spot when it comes to the issued MVUMs because the ones I've used in New Mexico are fairly inaccurate.
For example, the map shows a legal road, but the entrance has been blocked for years with a berm. Or, in other instances are some perfectly good trails that aren't on the map, but are obviously open for use (met forest rangers on them many times). So use them with a grain of salt! It makes it tough on us who want to tread lightly, and legally. Maybe it's just a New Mexico thing...