I routinely displayed the map on the 800 and the 1030 and have no trouble doing a century on one charge.

The Wahoos provide the same level/method of navigation that the 520 does. This method uses turn instructions embedded in the file. The Wahoo might display these in a better way.

The Garmins starting "numerically" with the 520+ can calculate routes on the device. The can also use the embedded instructions (Garmin calls them "course points") but they also can calculate turn instructions to follow the loaded track. They can also calculate a route to a place (like car units and phones do). This can create less than optimal routes but it can be a useful feature anyway.

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By default, the Garmins can display two data fields on the map screen. There are IQ apps that let you display more (the 530/830 screens might be kind of small for that).

The newer Garmins let you install apps to them (kind of like a smartphone).

The Garmins let you load maps to them.

I had a 800 that I very rarely had problems with. I have a 1030 that seems to be as reliable (I haven't done any really-long rides with it).

Garmin seems to need some time to shake-out the software in new units. It seems, maybe, that Garmin is getting better at fixing issues.

People like the Wahoo units. One reason they might be more reliable is because they don't do as much.