desmume and no$gba are both good i have both no$gba runs better on slower systems but does have some compatibility issues with certain roms plus you have to download an additional program to make it fullscreen or larger than the small screen it originally comes with the most popular of these would be no$zoomer or myzoom desmume is my favorite it runs most roms perfectly and has its own built in zoom program imo a better selection of rendering options overall i would go with the above and pick desmume i hope we satisfactorily answered your question.