I switched from Chrome to Firefox a few months ago. For the most part...it feels roughly the same but there was one subtle difference that finally irked me to the point of googling: having to right click on a tab to close it. In Chrome, when you hover over the active tab the close button pops up. This means you can pretty easily close multiple tabs by clicking the last tab on the right, clicking close, and then repeatedly clicking as the close tab appears in each successive tab. Of course, you could also right click a tab and click "Close tabs to the right" but meh.
As it turns out, Firefox makes customizing Firefox super easy. Click the menu, then Help -> Troubleshooting Information -> Profile Directory -> Open Folder and create a new folder called Chrome. In the new folder, create a file called userChrome.css and then copy and paste the following:
@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */
.tabbrowser-tab:hover .tab-close-button:not([pinned="true"]) { display: -moz-box !important; }
Restart Firefox and viola, close buttons on hover.
I didn't pull that CSS class out of thin air, you can inspect Firefox as you would a normal webpage by opening Menu -> Web Developer -> Inspector -> Inspect Menu (three dots) -> Settings -> Enable Remote Debugging & Enable browser chrome and add-on debugging. Afterwards, press Ctrl + Alt + Shift + I and press OK to inspect your Firefox window!