I have some lenses that I would term good or favorite because they seem to me to be lucky. That is, regardless of their technical merits or not, I always seem to get great pictures with them when I use them.

Now I would be the first to admit this is not scientific and indeed not necessarily that rational - but, in real world situations this feeling does result in me reaching for these lenses. And as photography to me is more about the pictures that I produce than anything else this is quite an important feature of what I would call a 'good' lens.

As an example, I have a m42 Schneider 35mm f2.8 curtagon that I can see is not technically the best lenses but does seem to get the pictures and have a higher hit rate than other lenses in that focal length.