Between those I'd choose Zotac, but Colorful has been making graphics cards longer than almost anybody else currently manufacturing graphics cards aside from AMD and Nvidia themselves. Since 1995 to be exact, while even EVGA didn't get their start until more like 1999. Zotac was established in 2006 but for the markets in which they have a substantial presence they are considered to be a primary manufacturer and from my experience they have had a much more solid track record when it comes to the quality, performance and longevity of their products than some manufacturers out there that are popular in the UK and EU.
I wouldn't hesitate to buy a Zotac card if I was in the market and the price was right. Colorful, I might be a bit more...