I tried Opera about 2 years ago. All kinds of crap kept setting off my warnings so I removed it all.
After 2 days of hair pulling, I've got Firefox back. Chrome lacked the auto fill forms and a few other things I got dependent on through FF. I ran 2 different deep scans for a total of 10 hours run time. One picked up 3 infections and the other picked up 27, 4 of which were Trojans.
I knew I had a problem when I couldn't even remove Firefox from add/delete programs. I finally removed the entire Mozilla folder from Programs, emptied the trash, rebooted and installed FF through Chrome. All is well.