Zsnesw is my favorite, coupled by Metal Worriors. For gameboy Advance, if your doing rips, go with visaulboy, but if you don't want any lag, go with NO$GBA... It's quite useless for resouces though.(no savestates either)
My favorite rom for gba is the megaman zero games. I like to waste time hacking roms and changing the sprites though... I made Link into a stripper one time :b