.itn is my route type of choice. The difference is a .gpx file sticks to the exact route no matter what, so if there are roadworks or road closures on route you're stuffed. The .itn route calculates a route from waypoint to waypoint and will re-route around road closures or roadworks. In the case of a waypoint being in the middle of roadworks or closure it will try to get you as close as possible, and you can delete the offending waypoint and carry on.