Of the 2 Canon lenses, general consensus is that the image quality is pretty much the same for both, but that the 100mm is easier to work with as you have to be pretty close with the 60mm to get 1:1 mag.
Don't forget to budget for a ring flash, or 2 normal flashes + a macro bracket. The reason you need so much light is that to get any sort of DOF you need to stop the lens down massively (small aperture = larger DOF).
Look at Mike's pictures and note how shallow the in focus area is.
hth.