With the exception of our sightless comrades, the most important feature all of us need in
any every browser must have is the ability to be "seen." To date I know of no other browser that will provide the instantaneous zoom-in/zoom-out via CTRL+Thumbwheel1 function that Opera does so well. No right-clicking!
At least on an annual basis (not necessarily when that newest FF, IE, etc. version comes out) I have made a pilgrimage to see if this singular intuitive zooming function has been replicated (dare I hope, improved!?) by any contender. Each time I have come back empty-handed and have once again settled down to another annum with Opera. I have used Opera since I paid a license fee of $35.00 and I have never regretted the purchase, but I digress.
Regardless of any whizzbang feature, if you can't see it, it's useless and for the vast majority (as in, "most of us") diminishing sight will be an eventuality.
I have tried numerous "magnifiers," but again, nothing is as intuitive, fast and simple as Opera in this wise. Opera also zooms every aspect of everything on the page too! Not just text as some do.
I do recognize that there are other browsers that perform better in some things than Opera for whatever reason, but if a browser lacks this intuitive zoom, it's a show-stopper for me.
1EDIT - simplified "CTRL+Roll-the-Mousewheel-Forward/Backward"