Frameworks are designed to help you get going quickly. Typically you want to choose one that has good structure and not base it too much off the UI components. The end result should be that you are customizing it to really fit your brand so make sure you are choosing one that will be easy to do that with. The reason being is if you are using Bootstrap or Zurb theres a 90% chance if I visit it I will be able to tell which one it is. That is TERRIBLE! Users can tell when things are just rehashed junk and want a unique branded experience. So I guess to me the best solution is to stop choosing a new one each time but build off of one and slowly deprecate it to make the experience your own branded one. If you want to switch to a new framework test it out on your next project but keep the principles the same.
If you are start working heavily with Javascript this same type of thought will really hold true. You dont want to couple your users experience too much based on one specific framework.
