The 60mm macro (which I have) is indeed nicely suited to the SL1. The 100mm is much larger, of course. What you get with the 100 is more "working distance" from your subject. Both the 60mm and the 100mm give you 1:1 macro closeups, but you won't have to get as close with the 100 because it is a higher focal length. So for bugs the 100 is often recommended.
Tamron has issued a revised version of their 90mm macro which now has image stabilization. It is much more expensive than the 60mm Canon, of course, but only somewhat more than the Canon 100 non-L, non-stabilized lens. You might check it out too.
Having said all that, if you are a relative beginner, I think the 60mm would be a good choice to start with.



























