I have both, both are excellent. It comes down to what you want to use them for, and partly whether you're shooting on FF or APS-C.

The 100L Macro is very versatile - besides the macro capability, it makes a good portrait lens on either sensor format. Its AF is a bit slower, so it's not ideal for shooting action. Obviously if you need to shoot 1:1 macro, it's the only choice...

The 135L is a great portrait lens, one of the best on FF. But IMO, it's a bit too long on APS-C, at least for indoor use. The wide aperture and very fast AF mean it's great for sports/action shooting, especially in low light, on either sensor format.

Hope that helps...