Tabbed Browsing in IE vs Other features

Somewhere in one of my posts, someone mentioned Tabbed Browsing and what is stopping the IE team from putting tabs in their browser. Then again someone mentioned that they can live without tabs but they don't like BHOs taking over their machines. So I thought why not open the room for discussion on this and ask everyone who feels one way or another about tabs about their opinion. The primary question is (subjectively) this:

What features should be ABSOLUTELY present in a browser to make that browser your default browser ?? Is it tabbed browsing? it is full control over BHOs? it is the best security and control available in a browser? is it fancy UI? is it the ability for the browser to conform to the specification to the very last, minute little detail? Is it a combination of these mentioned features? Is it something else?

In other words, what are the things that you want most in IE or want IE to improve?

Comments are welcome and appreciated.