Opera not responding to launch...What's the best browser to use?

Opera just went through an upgrade a few days ago. It worked fine before and up until today. Now, I click the app icon - a quick jump in the dock, but no response (and no blue dot to indicate it's open). I've tried right click and open, same thing. I've tried closing it, now I can't even get it to open on the dock again. What's up with this? Is this a good browser? I just started using this a couple weeks ago, mozilla fan personally - but I do like some of the features Opera has to offer. What's the best and safest browser to use? Are there precautions to take as far as security threats, etc. I've only been a MAC user for about a year now and as far as I've 'heard' the Mac pretty much takes care of itself. True?