EMarkM wrote in post #3908981
I have the 100mm and it is the single best lens I have ever owned or used.
And that is your truth, which is fine. 
It's the one that stays on the camera most out of all three of my lenses, because of its low light capability, all-round portrait and general shot goodness, and crisp, sharp macro shots.
The 60 is a better all-round lens on APS-C, just like the 100 is a better all-round lens on FF. The 60 is also slightly better than the 100, but you need to pixelpeep to the extreme to see the difference. Bit of a moot point IOW.
I considered the shorter lens, but am glad I went the extra mile and bought the 100mm: less chance of scaring off the little insects and birds!
I've always found this an interesting statement, whenever it was made. I always found that anything shorter than 200 to 300 mm scared away skittish insects, and I have never been able to shoot a bird with anything shorter either, unless it was used to people. Oh, and I do shoot insects with an MP-E 65, occasionally, talking about being close to insects. 
It is not an extra mile BTW
, it is only about 4 cm of additional working distance at 1:1. Again, personally I don't think the difference between ~10 cm WD and ~14 cm WD is critical. And a 50 mm is fine too, which is something I have used in the past a lot for macro shots on film, FF IOW.
The only three disadvantages, none of which put me off: price, size/weight, 100mm on a 400D = 160mm, which means you need to back up a bit for portraits.
You don't always have space to back off, plus, personally, I prefer the 60mm perspective for portraits on APS-C. I was used to this FL in FF equivalent (yes, 100 mm in FF
) back in my film days, and always loved it.
So do I. After all, I have both the 60 and 100. 
In the end, it is about what you find important, but that is true with any lens.
Kind regards, Wim