10.6 beta may be has some bugs because its still in beta stage but Opera stable edition haven't got any bugs ( As far as I know ) I'm Using Opera about 3+ years
having a faster browser shouldn't be the priority.....
but to have the most safe & private browser.....and nothing beats Fire Fox in that department.....
not to mention how flexible Firefox is.....
a difference of a few seconds may be semi important in the long run.....but its better if in those extra seconds were used to protect ur privacy and other details....from annoying spammers and advertisers....
When comparing with Chrome and Opera, Firefox is the fastest and the worst web browser i've ever seen (this damn shit stucks stucks stucks and stucks all the time)....