Welcome back to the emulation scene! MAME is certainly the best option for arcade games of course, along with many of the more 'obscure' but decent systems that don't get much coverage and attention such as Bally Astrocade, Fairchild Channel F, along with many of the classic computer systems, most of which I've never heard of However, for most of your emulation needs, Retroarch is probably the best choice, and for the newer consoles (Dreamcast, Gamecube, PlayStation 2, etc.) stand-alone emulators (Dolphin, PCSX2, etc.) are the best way to go. Have fun!