I like osmand because during several lanes it highlights the lane to go to. I noticed organic maps had something similar today when i tried it, though ill need to do more testing to see all the features.
I think organics maps has a a good clean ui. Improvement woukd definitley be compatibility when using the voice for navigation, a bit laggy but maybe ill need to adjust rhvoice. Also im seeing if it has the show the next turn on a small icon of some sort.
Osmand is good overall but it can get too cluttered real quick. Its been getting a bit slow but maybe some tweaks will help.
Also i have contributed to openstreetmaps especially toward small businesses to make it easier to find.