I would stay neither. Those adaptors are ok, but just ok. The will leave the edges soft/fuzzy. For the Canon 50mm it would make the lens a 55mm. Are you aware of the conversion rate on cropped sensors?
On your Canon camera a 50mm = 80mm. You times the focal length by 1.6. So 50mm x 1.6 = 80mm. So 50mm x 0.7(wide angle adaptor)= 35mm x 1.6 = 55mm = not wide angle. Sure you could use the .45x lens, but that will have some issues too. These adaptors are a cheap way to get a lens. For camcorders that don't have a removable lens, they work. For SLRs, suck it up and buy a lens. Trust me, it will be worth it. Help at all?