I have used, IE,BTYahooBB, Firefox, Deepnet, and now Trying out Opera.
My first opinion is that Opera is the least user friendly.
Rate (1) Firefox), (2) Deepnet, (3)BTYahooBB, (4) IE in order of User Friendliness, and security. Opera is yet to be rated if I ever learn how to use all its functions. I am not enthused at the moment!