The few such garages and sheds I did for myself and for a couple of friends and neighbors years ago I used PVC conduit. Although perhaps quite adequate for most domestic garages, I'm not especially keen on seeing T&E just surface run. By the time you mess around with terminating SWA into glands and getting it cleated looking reasonably straight, I think it takes as much if not more time as installing PVC conduit and pulling singles. Steel conduit is obviously more time-consuming, more exprensive, and seems a little excessive for a typical domestic garage.