Tamron makes good lenses too and very affordable. However, depending on what type of macro work you do, the min focus distances (5 feet on my 75-300) can limit the angles you can shoot from. If you are going to be doing closeup flower macros it 's not going to cut it.

Now saying that, the min focus distance is great for shooting butterflies and birds from a distance without disturbing them. So it will depend on what type of macro work you want to do.

I do love my Tamron for what I do with it and for the price/performance it can not be beat.