Recently Google removed the option in Chrome to go 'back' by hitting backspace, and instead changed this to 'alt + left arrow'. The argument was made that too many people accidentally go back when deselecting a text window by accident. There are arguments and counter-arguments for both sides, but Google should have left the option to retain the backspace shortcut.
I don't like a lot of things about Chrome anyways, so that was just the cherry on the cake for me to migrate away from it. I've always liked Opera pre-webkit when it was on Presto, so the fact that Vivaldi is now aimed to revive a lot of Opera-esque features is great.
Plus with Vivaldi you can tile multiple webpage sessions in the same window: great if you want to view multiple websites simultaneously side-by-side.