Originally Posted by
Carbonfiberboy
For platform, I use RidewithGPS.com, premium account. I have hundreds of routes saved there. I move the route(s) to my Garmin 800, purchased in '10. The Garmin Edge 830 is the newest in that line. On a long tour, I break the route down to sections of under 400k. I usually pre-plan the whole tour, but sometimes things don't work out that way. Being able to create and upload new routes at a WiFi hotspot would be wonderful.
You may want to investigate the possibility of uploading a course via Garmin Connect. AFAIK, Connect, on a phone, can import a locally generated GPX file and add it to your courses collection. It can also push a course to a connected device. I'd like to be more specific but am currently travelling... will update when I get hold of a more recent watch (Fenix 5) and let you know if generating a course on a phone and pushing it to this device works well or not (on/offline). You may also want to explore Garmin's IQ store. There are hundreds of apps and add-ons for fitness watches. Might be something for bike computers as well.
This being said, I'd suggest that you consider a Forerunner 935/945 or something from the Fenix 5 family instead of a bike computer. The only drawback that I can think of is their smallish screens. OTOH, bike computers are useless for running. A smartwatch + smartphone covers most use cases. Assuming network availability, you could generate a route on rideWithGPS, export to your phone, import with Connect and push it to your device.