You are either a keyboard shortcut person or a mouse/touch-pad person. If the latter describes you, I have a Firefox extension that may be of some interest. TabFlip lets you switch tabs with a flick of the mouse.
After installing TabFlip, you can immediately get to the flicking or, as the developer calls it, flipping action -- no restart is required. To switch tabs, hold down the right mouse button and give the mouse a flick horizontally. Flicking to the right moves you to tabs to the right, while flicking to the left does the reverse.
The same action can be performed on a touch pad, too, but with more difficulty and only if you are using a Windows PC. I had no luck with the extension on a MacBook Pro touch pad, and I found it harder to perform the right-click-and-flick gesture on a touch pad than actual mouse. And while the extension works on a Mac with a mouse attached, the right-click pop-up menu gets in the way. It pops up when you initiate the flick command and stays on the screen even after you arrive at another tab. The right-click menu doesn't surface when using TabFlip on a PC.
There are a few settings of note for TabFlip. Check the box for the Wrap setting, and you'll wrap around from either end of your tabs to the other side instead of hitting a dead end. The Scroll Flipping setting is tempting to enable because it lets you perform a two-finger swipe on a touch pad or touch screen to switch tabs. Unfortunately, it disables the two-finger vertical scroll function you likely use to scroll up and down Web pages. Lastly, if you find you the extension is too sensitive and switching tabs when you don't intend it to, you can adjust the number of pixels a flick must cover to register as a command.
The first two settings are enabled by default. They set the areas -- tab bar or Web page -- where the extension will read your gestures. I don't know why you'd want to use the tab-bar flipping. It's a narrow target to mouse to in order to switch tabs, and the right-click menu gets in the way there, which is doesn't do when performing the same gesture anywhere on a Web page.