No, colorless diamonds are not necessarily "better." Color is just one element of the 4Cs, which (along with color grade) include cut, carat size, and clarity.
When you consider purchasing a diamond, carefully weigh all of the elements of the 4Cs along with your budget. Colorless diamonds are quite expensive, and depending on the diamond shape you choose, color may not be as important as cut or even clarity.
So ultimately, whether or not a colorless diamond is better depends on your preferences, budget, and the diamond shape you want.
The Gemological Institute of America (GIA)
The 4Cs were created by GIA founder Robert M. Shipley. Prior to Shipley's 4Cs, there was no standardized way for diamond merchants to grade diamonds.
According to the GIA website, "Under Shipley’s direction, the term 4Cs became part of the American gem industry’s vernacular, popularized through advertising campaigns, lectures, and GIA education courses. Within decades, they were integrated into the international nomenclature as well."