MAME Classic has been one of my favorite frontends for quite a few years now. Not a lot of bells and whistles, just a simple User Interface.
* Independent default options for Raster, Vector and LCD games
* Software list support with manual editing for command-lines MAME Classic cannot determine
* Favorite game lists
* Custom settings for individual games
* Finds ROM changes between MAME versions
* Numerous game filters
* NPlayers.ini and Catver.ini support
* Icon support (requires icons to be unzipped in a ICONS folder in your MAME directory)
* Game information (requires the history.xml, mameinfo.dat and cheat.7z files)
* Alternate directories for each directory in the mame.ini file
* Multiple ROM directories
* ROM and Sample verify with search for bad sets
* Screen Shots
* Ability to find and delete ROMs which are no longer supported in MAME
* Maintenance to your MAME directories
* No setup required so can be run as a portable program