Get this one http://www.the-digital-picture.com/R...ns-Review.aspx
IS is nice, but most macro things you don't need it. The AF of this lens is really fast if you set the magnification limiting switch. I use it for many things other than macro. I use the one above for portraits, macro, and closer macro (with 1.4x TC and extension tubes). I also reverse a 50mm 1.8 on the lens every now and then. The difference in IQ between the L and this one is very minimal and I have not seen the need to upgrade to the L version at all. I didn't get the 60mm macro because I wanted some working distance between my subject and I. 180mm macro is big and heavy.
Another lens to consider would be the Sigma 150mm OS version. I have heard great news of this lens, but haven't tried it. It is very sharp and has OS. I believe it is cheaper than the 100mm macro L. Bryan reviewed it here http://www.the-digital-picture.com/R...ns-Review.aspx.
Lastly, another lens to consider is the Tamron 90mm Macro. Is has VC, inexpensive and very sharp.