Don't use either!
There are a squillion route planning apps and programs (remember them?) out there, almost all of which are better than doing it on the device.
Others have used Tyre and MyRoute to great effect. No-one (except 3 hikers in the wilderness USofA) has ever used Garmin Basecamp to any effect. Can't remember which Garmin the Nav iv is based on but if it uses Garmin's old Mapsource, then that is an excellent if clunky route-planning tool but the later devices don't work with it!
I did plan my return route from Llandudno, post Wrinklies run, on my Garmin 660 and it produced exactly the 240 mile, winding route I wanted with a mere 11 waypoints and no hassle whatsoever, which is more than can be said for trying to get the Wrinklies routes into the damn thing in the first place
However, getting the route correct on such a clunky and small device is never easy and I cheated by using Google maps on my iPad to see the detail and resorted to my Ordnance Survey maps for the overall shape of the route.
And you are correct, it is a very subjective issue and quite 'them' and 'us', so I'll not let myself get dragged into the 'mine's better than yours' debate