I know you already decided - and beautiful coin by the way - but when building sets, especially copper where color comes into play, it's going to depend on the rest of your set. A 63RB is going to stand out in a set of all brown coins. A brown coin, even a high grade 64 or 65, will stand out amongst a red brown set. So, if you have mostly AU coins, I'd stick with that. If you are building a mostly uncirculated set, stick with those wherever you can afford to.