Too bad you're not getting much help here, because this is a terrific topic. I think you understand a good deal about using the phone for navigation already, but I will offer these thoughts. Although not 100% familiar with the other apps you mentioned, I will state unequivocally that Osmand can perform the following functions very well:
1) Navigate a route downloaded from a ride planning service such as
www.ridewithgps.com.
2) Use a self contained data base.
3) Store the route as you ride for later analysis by ridewithgps or a similar service.
4) Provide both turn by turn oral and visual instructions.
Last summer, I rode a three day trip to Yosemite Nat'l Park using only Osmand and no physical maps. After receiving the three gpx legs from my buddy via email, I stored them within the app and set off riding, swapping between the self contained maps and topographic on line maps as desired. This worked very well.
I have used Osmand all over the world and though I have donated to the cause, I have never been required to pay for maps or the service. You can download the latest free version by searching on "latest Osmand nightly build" and selecting the development version.
Limitations: although you do not need a data or cellular connection and could very well use the device in airplane mode as I do in Europe, you do need to constantly receive GPS, and if you desire the navigation assistance, you need to have the screen on. This limits you to about five hours max on the battery. Fortunately, however, Android devices allow access to the battery compartment, unlike iPhones, so I always carry one or two spare cell phone batteries. If you have good kharma, your local cell phone provider may actually give you a spare battery from one of their returns.
Also, the voice navigation system, although quite robust, does not provide street names, only turn signal directions.
Again, I have used the Osmand system extensively in many European countries, Israel, Australia, and the United States, and strongly recommend checking it out. However, the app has so many menus and features that you need lots of practice with it before setting out on a long journey.
Just a few takes on what I know of the other apps. Google Nav does not allow navigating a pre-planned route. You must give it the destination and it will take you there by direct routing. Mapmyride does not offer an Android navigation app. You can use it for ride planning, but ridewithgps does a much better job. As for Strava, you would use it to record your ride and compare your performance to other riders in the Strava community, but the app alone does not provide navigation assistance. Finally, after checking out the massive Orux program, I see that it does provide navigation assistance, but only through a trick method of switching to Google Navigation. Apparently you have to manually select the navigator for each successive waypoint. Also, Google Nav requires a data connection. These limitations make Orux impractical, IMO.
Bottom line: Osmand costs nothing and can navigate to any point or follow any route worldwide with no signal other than GPS. No other app does this.