This thread would have been SO useful for me when I first bought my system. I learned the hard way that much of what the pros here said were accurate....... too many of us newbies (like myself) find it hard to break away from what we know is a good lens topside.....things are simply VERY different underwater. My Nikkor 105 VR is my fav macro lens topside......UW though, the 60 is WAY easier to use and so much more versatile .....here are my three armature examples...I look forward to see what the pros like Alex can show us.... In fact, this would be a great thread for various lenses (especially with insight on the photog's distance from subject too if WA) ;
I think it really depends where/what you shoot, I actually really like the 105mm for macros place like Lembeh and Anilao for example.
The first lens I took was the Sigma 105 (and I bought the sigma vs the nikon for $ reasons) and I supplement it with a nexus wet diopter sometimes. The 105 is great to have that extra reach for shy and relatively small fish or portrait of fish of moderate size or because what 60mm brings you too close and (warning I'm talking macro here
).
Typically I have found that the 60mm sometimes bring chaos around anemonefish in some areas and they get way too agitated or too scared.
The only grip I have with the 105 is that it is a bit noisy and slow to focus and you need to have a good focus light with wide beam when in low light otherwise it can hunt badly (if you are trying to shoot a black nudi or a black frogfish in low light, be prepared for some frustration), in comparison the 60mm is pin point accurate, quiet and fast (though, it is sometimes challenged by those black on dark species too but much less). It could be that the D80 is responsible for part of that as well.
With the Sigma 105 EX DG:
http://www.flickr.com/photos/86328154@N00/...57617545943509/

http://www.flickr.com/photos/86328154@N00/...57617545943509/

With the Nikon 60mm AF-S:
http://www.flickr.com/photos/86328154@N00/...57617545943509/

http://www.flickr.com/photos/86328154@N00/...57617545943509/

You can browse in the whole set to see 60 vs 105