You can't really answer the question unless you say what the difference is though. Each set has it's own goal and thus results in a different set of roms. Goodtool sets are intended to be the be-all end-all set. They try to have every single game and every version in the set. So as a result you will end up with 20 versions of super mario (USA, JAP, EUR, USA Hacked version 1, JAP Alternate ending version 1, .......). The set will be structured so that each game has all versions of the roms zipped together. GameEx can handle this and will list each one for you when you select that game (if you are a registered user). NoIntro sets are designed to be a no-bull set. They include only the "best" official release of each game. I think they still include the different regions in the set so you will have USA, JAP, EUR, WORLD, etc, but it will not include the hack were Mario looks like Barney . TOSEC is similar to NoIntro AFAIK, except they include other systems that used optical media as well. For newer consoles (Dreamcast, PSX, etc), TOSEC is the only way you are going to find all roms together. I don't think the other sets do these much larger collections, so TOSEC is the only game in town. But, like Flash said, you won't be able to find all consoles released from all 3. As a result, you will end up with a mixed and matched collection either way. Since I'm not familiar with TOSEC, I can't comment on where it would fall in my priorities accurately. As a result, my order of preference would be: 1) NoIntro 2) GoodTools 3) TOSEC