opera 11 or firefoxOpera 11 or Firefox 3.6? Which browser is better?

I'm struggling between Opera 11.11 and Firefox 3.6
Which one is better and why? Please give info about speed, reliability, features etc.

PLEopera 11 or firefoxASE DO NOT MENTION OTHER BROWSERS SUCH AS SAFARI, IE, CHROME ETC. JUST FOCUS ON OPERA AND FIREFOX

Also, I'm talking about OPERA 11.11 andopera 11 or firefox FIREFOX 3.6... not Opera 10 or Firefox 4!


Thanks
Two thumbs up for firefox 3.6 nd half thumb up for opera 10