My $0.02 worth??? I'd choose the attic over the garage, since the garage is more likely to have reactive metallic items around it, a car, motorcycle, roll-around tool boxes, aluminum garage doors, more electrical wiring, florescent lights, etc. Things to consider in the attic??? Is the roof standard wood and shingles, or tin? How far are you away from CATV, or DSL, MODEM's and routers? Is the fibre glass insulation, (If any.), covered in aluminum foil? Some things to consider, but I've fully made use of an attic to mount CB antenna and HAM antennas, and FM / TV antennas, and with decent results. On possible mounting for a loop is to mount it hanging upside down from the apex of the rafters. Good luck, and HAPPY DX'ing!!!!