kml: Easy to import to GE and (with utility available in Project) to convert to shp file, but only generalized (data loss) and with overhead

gpx: Most likely, future standard and no generalization, but need to convert (no utility available yet) and with overhead

trk: Easy to handle and no loss of data, but has to be converted manually, which requires know-how; recommended by Consultant for data transfer from GPS to GIS