Good quality white chocolate will have a higher amount of cocoa butter in it. Ideally you want white chocolate with around 29-30% cocoa butter. The higher the amount of cocoa butter means it will melt more easily and evenly. Many of the quality brands will list the approximate percentage. Some brands don't list the percentage of cocoa butter. In that case, I recommend going with a good, quality brand. Ghiradelli, Valrhona, Callebaut, Lindt and Scharffenberger are all good brands. I would not recommend using white chocolate chips for caramelized white chocolate.