I like geometry, circles, minimalism, simplicity and easy to recognise logos
Should be, desrcibable, memorable, scaleable, work in colour and black and white, and be relevant to our industry.
I like clever logos that 'wow' people like the Fedex logo with a hidden arrow or the coolness of the illy coffee logo, here are some examples:-
http://designshack.net/articles/graphics/50-fantastically-clever-logos/