It's honestly always been CTRL+TAB to move to the next for me, really quick with the left hand and three leftmost fingers.
The problem is that this is sort of the "standard" across software projects where you have anything resembling tabs now.
But I will say, again, Google's ridiculous decision to remove backspace to "go back" from Chrome, and on top of that mapping it to the abominable ALT+Left? That one definitely requires both hands, removing one from the mouse for no reason. So now I just right-click and then left-click "Back" on the context menu. Grrr....
We must have very different keyboard setups.
I don't constantly have my right hand on a mouse, as I'm on a laptop with a trackpad in the middle. So I can easily use the keyboard with both hands, and Alt-Left is completely normal for me (2nd finger on right Alt, 4th finger on Left button). Similarly, when switching tabs, I can put my thumb on the right Ctrl button, 2nd finger on PgUp and 3rd finger on PgDn to easily switch tabs back and forth. However, going back and forth with Ctrl-Tab/Ctrl-Shift-Tab requires me to keep holding Ctrl with half of my thumb, while putting the other half onto and off of the Shift key. It gets painful, not to mention confusing.