As AC says.. Bell and Telus share towers not Rogers, that rep is feeding you BS. I find Rogers to have a better signal out in the fringe areas up north. But they all have dead zones. There is a spot in Mississauga where I take my kids swimming and my Rogers phone is pretty much dead, where Bell/Telus is almost 5 bars. If you want to see tower locations in your area you can check this map linked below, but topography plays in to it too. My cottage is near a Bell tower but because of the poor line of site to the towers it was pretty much a dead zone. Also, ironically the signals used to be better with the older technology. My 3G phone on Bell or Telus worked just fine at the cottage, once the H+ and 4G phones came out the signal immediately got worse, they don't have the same range. I ended up switching my company's corporate account to Rogers so I could have a signal at the cottage.
http://www.ertyu.org/steven_nikkel/cancellsites.html