I am now eager to leave Chrome; several add-ons will stop working, including stylish (I need to make a readable font and larger font sizes, not to be forced to whatever some 20-year-old eyeballs thinks looks good enough to them), etc.
But: I need to be able to move to firefox with *everything* brought over. Including the open windows and tabs.
Tabs being grouped together is a big thing for me. A given window having a set of tabs means those tabs are related to each other, and I want them to be reopened together.