Twenty Twelve was the best by far.

It tried to impose the least design on people, and who really wants to use the default theme as is anyway?

What they really need to do IMO is get rid of default themes and create a great starter theme and/or framework (that doesn't have to be a parent theme), one that is designed to be extensible and allow designers to easily "skin" it than offer yet another boring default theme.

JMTCW.