I originally got interested in the Opera browser because I heard that (at least at the time) it was the most compliant with W3C HTML recommendations and should therefore be useful for testing website coding. I also obtained (and will be retaining) a copy of Opera Mini. I don't know if it's still supported, but I use it on my desktop computer for testing what my websites will look like when linearized and displayed on variously-sized small screens.
I also use Opera-mini on my phone. Works well. And I think it is still supported, as I get periodic updates on it.