None of the above:

Free Commander
AutoHotKey
VideoLAN

A bit surprised that no-one mentioned VideoLAN (a media player)

If you like AC Browser plus, you might be interested in the option to alter the menu entries to suit your habits/taste better.  You can go to the subfolder: International\English\translation.ini.  Open that file in a text editor and you can change the menu entry text.  There are still a couple of items that cannot be edited in this way, but I found the odd English of the original menus a bit annoying.  This is where you would create a translation file for an unsupported language if you were so inclined - some details are in the file header.  I like some of the tools for file management, but the shortage of ways to invoke external editing software is a drag.  I found the lack of hotkey customizability not to my taste, so I was taken with the ability of Free Commander to make whatever hotkey you like work for the operation of your choice.  Free Commander also allows you to use the built-in viewers or invoke an external viewer like Universal Viewer (a Total Commander connected program - uses several TC plugins).  You can also specify programs to open a user-defined list of file types for editing (F4 key - or whatever hotkey you want to use).  Free Commander also has a portable version, but one warning, the .ini file is not the same as the non-portable format, so you have to enter your customizations separately for each - you cannot just copy the .ini file to transfer settings.  I am a keyboard fan and with the navigation keys definable to keys that make sense to me, I am in 7th heaven!

The one thing that I appreciate is the ability to customize the interface.  Arrange the menus/hot keys/toolbars to suit my own peculiar logic.  Failing that, visual cues and meaningful descriptions that prompt the user in the use of the software are good.  Then too, following common usage for common functions is only natural. (I'm still pissed at M$ for not using Ctrl+Q for the exit shortcut when it introduced Win 3.0 - I mean have you tried to do Alt+F4 without looking, and that combo is just so obvious a choice for that function it leaves me gaping!)