Torbjorn is not bad for beginner as long as you actually play and dont just stand near your turret. His left click is the real deal.
Reaper is ok early on but you will be bad until you learn the maps.
Junkrat can be good for newbs too.
Torb needs map knowledge to play well too, much moreso than Reaper IMO - you can't just plunk a turret down anywhere and expect to be useful. At least with Reaper you can just melt face then shift out and run away.