Choose the range first, then the glass
Start with the range, not with the single glass. RCR builds ranges you can keep adding to for years, and the cut sets the character. Melodia is the broad middle ground with a fine diamond pattern and runs from a 5 cl liqueur glass to a 65 cl gin and tonic bowl. Timeless and Adagio are sharper and more modern, while Opera and Brillante have a classic cut. Etna and Alkemist have a heavier base and are built around spirits. If you want colour, look at Gipsy, Maori or Pedro & Rosa, where the tumblers come in a set of different shades.
RCR is generous on capacity. Tumblers run from 21 to 42 cl, long drink glasses from 34 to 44 cl, and the wine bowls go well beyond 50 cl. For whisky neat, a tumbler of 30 to 35 cl is pleasant, because a large ice cube fits without filling the glass straight away. For a gin and tonic with plenty of ice and botanicals you want that 65 cl bowl instead.