[eeyore]

Originally Posted by BillyPilgrim

I don't think you can go wrong with any of the Sigma range. They are excellent lenses.

All you really need to consider is the working range. The shorter the lens, the shorter this distance will be so if you are wanting to photograph nervous insects you might be better off with the 150mm or 180mm.

good point - although if you need to buy a shorter lens for reasons of cost as they are f2,8 lenses you can also get excellent results by using a 1.4 or even 2x teleconverter to extend you minimum working distance. (most of my macro shots on here are taken with a tamron 90mm and 2xtc)