All macro lenses all brutally sharp, so there is little gained discussing/obsessing sharpness comparisons. Here's a different practical way to compare macro lenses: Consider working distances (WD) versus prices when these listed lenses are close-focused at full 1:1 magnification:
EF-S 60mm Canon = 10 cm WD @ $440
EF 100mm Canon = 15 cm WD @ $480
HSM 150mm Sigma = 20 cm WD @ $620
180mm Tamron = 26cm WD @ $690
EF 180mm Canon = 25 cm WD @ $1,300
WD 10cm. Unless you need this 60mm EF-S macro for specific uses, the 100mm Canon macro is a better all around WD value and flexible use for most people. The 60mm is limited to EF-S mount Canon cameras.
I carry the 60mm macro when working in the field with no tripod, as a portable, hand held macro, letting me use it at moderate shutter speeds without excessive camera shake image blur, as part of a portable field travel kit. It is the only Canon macro that let's you leave on the filter while using the 14EX or 24EX macro flash units.
If you vacation/travel with a wide angle (e.g., 17-40mm) and telephoto zoom (e.g., 70-200mm f/4) this 60mm becomes the lower (if not low) light lens as well as the macro piece of the kit.
Those who long respected the Nikon 60mm f/2.8 micro Nikkor waited years for Canon to make an equal, it just happens to be EF-S mount.
WD 15 cm. You only pay about $40 to add 5 cm of WD from Canon's 60 to 100mm macro lens. Due to floating internal elements, the Canon 100mm has a shorter than 100 mm internal actual focal length at 1:1, likely 70-80mm, maintaining a good field of view while providing 14.9 cm WD. This is a GREAT flexible lens. 5 cm is a big 50% WD distance gain.
WD 20cm. Pay additional $140 for another 5cm WD step gained from the Canon 100mm to the Sigma 150mm. The Sigma comes with a hood, tripod mount, HSM auto focus with full-time manual over ride (I manually focus much of the time), making it an very good middle contender, if it fits your needs. It is the first Sigma lens ever I used that contributed something important to photography performance; not another a “me-too” price-point product. Sigma4Less.com sells it reasonable. You need the Canon 72mm macrolite adaptor to connect the 14 EX or 24 EX macro flash.
WD 25cm. Step up and you pay an added $700 for the next (last) 5 cm WD gained between the Sigma 150mm and the Canon 180mm. This is an amazing optic, little diffraction even when stopped down to f/22+. Ultimate WD.
The longer focal length makes it much easier to compose shots by isolating subjects, eliminating clutter, and much easier to get the lens plane position parallel to where you want the maximum depth of field on the subject.
It's big and long and prefers to be used tripod mounted, except when "butterfly hunting." Works with Canon 1.4x teleconverter as a bonus. The last macro lens you'll ever buy. . You need the Canon 72mm macrolite adaptor to connect the 14 EX or 24 EX macro flash.
WD 26 cm. The Tamron is the longest WD versus price value winner, but I did not use nor consider it because a non-standard lens filter adjuster may prevent using the MT 24-EX Macro Flash.
What is Working Distance? WD is the distance from the FRONT of lens element to the subject when the lenses are focused at their closest focus 1:1 magnification. Macro lenses all focus continuously to infinity also, but we are only calculating close focus distance above.
= published close focus spec for lens - lens length - distance between rear element and sensor or film plane (which is approx. 4.4 cm for Canon EOS camera system.
WD is a BIG limiting use factor (in addition to the full 2 f/stops of light loss @ 1:1 magnification), so get as much WD as you can afford.
If you're serious about macro, try not to buy a macro where the lens barrel length changes during focus. For casual macro users, this is OK (like carrying the old Canon 50mm f/2.5 in a pocket out for a hike).
More Fun at Less than Life Size
When we mean macro, we mean life size reproduction, (1:1) magnification or greater. There is loads of fun "close-up" photography at less than life size, say 0.25x to 0.70x (butterfly and dragonfly hunting range) that you can do with close-up filters (diopters), close focusing zooms, etc. A cheap Canon XXXmm-300mm zoom with a Canon 500D ($140) +2 diopter makes a good butterfly hunter, providing about 0.4-0.7x depending on focal length and lens.
Using a wide angle lens close-up enables “a thing in its environment” close-ups,” which are useful and popular.
Hope that helps. Jack