I wish I could use Vivaldi, it seems like a nice browser for power users. Unfortunately it's closed source (besides the Webkit parts). Considering how much sensitive information goes through a browser nowadays, I would never consider something closed source. I'm sure Vivaldi has no intentions of becoming "evil" like Google, but because of its closed source nature it wouldn't be hard to slip a tracker or two in the br…
I don't know what browser you're using, but assuming chrome : it's not open source either. Chromium is open source, but Google Chrome is proprietary, much in the same way vivaldi is. If you want a truly open source modern browser, the only options are chromium or firefox these days, AFAIK ? (If you know an alternative I'm interested !)
On Android I can recommend Lightning: https://github.com/anthonycr/Lightning-Browser