what is right: none of us is perfect or none of us are perfect ?
none of us is perfect
Because none means not one wich is singular.
You wouldn't say: Not one of us are perfect.
Most of the times, the choice between singular and plural with collective nouns will depend on whether you want to speak American or British English.
American English tents to use the singular conjugations for collective words, while British English will prefer the plural conjugatoins.
For this none case, this text seems to say that you can use either option depending on what you want to emphasize: a whole group or all elements - http://dictionary.reference.com/help/faq/language/g11.html