Any manufacturer is capable of producing fine lenses, and also dogs.. even nikon has a couple of crumby lenses in their nikkor line... But I have one tokin Nikon 12mm-24mm. I also have two raynox macro lenses that I use on a panasonic lumix fz30 that take great bug pics. Each of those companies have also produced some real lame designs, too. Best to research each lens as a stand alone.. the web is a great resource and the site:
http://www.dpreview.com/ is your friend, especially the user forums...
Best,
John