i think after rereading my post it deserves a bit of explanation- i prefer canon's build and support qualities over that of sigma, however some will argue that they prefer sigma. canon and sigma can be very close and debatable. check fred miranda's reviews.
I tend to dislike tamron as I find their glass to often be soft and slow. Phoenix even moreso.
as for the macro, im currently using the 100mm f/2.8 made by canon to do a series of macro projects. I really like this lens, though at some point in the coming months I will be adding the 180mm L glass macro to my kit as well. I'm finding that I enjoy working on macro projects quite a bit, though this is something very very new to me.
There is a macro forum over at fred miranda that you should check out with a lot of good resources there.