Google.com, by far.
The two biggest challengers in 2005 are MSN & Yahoo — but compare the search results pages for any subject you know well. It is obvious that Google is far ahead.
If you need specialized searching, check Phil’s Search Engine.
I have used MSN’s hotmail for years. But is Google’s Gmail better?
Not quite yet, IMHO. But I have a Gmail address and can get you one. If you want to try it, email me.