When comparing MAPS.ME vs HERE WeGo, the Slant community recommends MAPS.ME for most people. In the question“What are the best offline GPS navigation app for iOS?” MAPS.ME is ranked 1st while HERE WeGo is ranked 2nd. The most important reason people chose MAPS.ME is:
That saves a lot of download, e.g. from ~500MB in other applications it is reduced to ~50MB for German surroundings.
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Pros
Pro Very detailed selection of areas to download
That saves a lot of download, e.g. from ~500MB in other applications it is reduced to ~50MB for German surroundings.

Pro Includes offline routing and turn-by-turn navigation
Users without a data connection can still use the app for turn by turn directions, which is great for those that travel or use a device that does not have a cellular data connection.
Pro Obtains data from community-based OpenStreetMap
MAPS.ME uses data from OpenStreetMap, meaning the data retrieved from that service is a community-based map. Anyone can freely edit and contribute to the map, a map concept that is similar to Wikipedia.
Pro Fast rendering
By using compression of the map data, MAPS.ME is able to speed up the rendering of their maps to one's device. This allows for a quicker feeling app.
Pro Optionally can download traffic information
And showing it color-coded (Google-maps-like) on the streets.
Pro Discover nearby feature
Shows a nicely organize list of interesting places to visit close to your current location.

Pro Matching modern material-like interface
The design of the app uses a material-like interface making for a close to native looking experience on Android.
Pro Offline vector maps
Automatically downloads vector maps for offline use.
Pro No nagging advertisements
Pro Easy to install
Pro Easy adding/editing of bookmarks/favorite places
Click on the map and you will have the option to Bookmark, Route From, Route To. Having selected Bookmark simply offers to edit it, e.g. give it a different name.
Pro Allows to edit OpenStreetMap data
It is possible to add new and edit existing POIs in OpenStreetMap database using a nice interface.
Pro Night mode
There is a night mode option.
Pro Integration with booking.com
Displays information from booking.com about hotels and apartments.
Pro Gives traffic and public transport information
Needless to say that these features will give you better and more up to date feedback when you're online, but you can still use it on offline mode. You can think about alternative routes or which public transport would be best for you to use, so you'll always have choices.
Pro Be able to download and use maps even on offline mode
Another good thing about this app is that you can download a map of an entire country of just a specific region, such as a province or state. So if you won't be needing a complete map, this will save you a lot of storage space. But you should check the file size when you're planning to download several regions because you may end up with a bigger file compared to just downloading the map of the entire country.
Pro Get to your destination easily with its turn by turn navigation
It has a very convenient turn by turn voice guidance so you can keep your hands on the wheel and be stress-free while you're driving. If you just plan on walking or commuting, then you'll be able to know every step or transfer that you need to take and when.
Cons
Con Poor response time to recalculate the route
Con No option for satellite/aerial/topographic imagery
Not as useful for navigating while hiking/climbing/etc.
Con Very slow search and route calculation
Probably because MAPS.ME has more POIs in its database which ends up with all searches and route calculations being very slow.
Con No display of speed limit
Neither the next nor the current one.
Con No way to distinguish between fastest, efficient or shortest route
Con Very limited options
E.g. no way to hide certain buttons like the traffic button, or to configure the language used to display city names.
Con Sometimes very strange suggestions
E.g. when not using the suggested route, Maps&Me continues to request to turn even if you are more than 100m after the cross-road.
Con Favorites are a little bit too hidden
Because they are stored in groups.
Con Traffic information is not available in all countries and cities
Source of traffic info is a trade secret this feature is only available to some selected cities.
Con No lane assist
Con Being based on OpenStreetMap data can be lacking
The use of OSM also has the drawback of many places not getting the attention needed for updates. Depending on the geographic location OSM may have the most detailed maps or the most bare/outdated map.
Con Does not show images offline
Does not show images offline if supplied in standard kmz file. i.e. zipped kml plus image folder.
Con No tourist detail maps
