Zalto Universal is one shape that somehow flatters everything. It is so thin you barely feel the rim against your lip; the wine seems to land directly on your palate. The slight tilt in the bowl is designed to direct aromatics straight to your nose. The downside: hand-blown, lead-free crystal is fragile. Treat it like stemware that is also a sculpture.
Riedel Veritas is engineered. There is a different bowl for Cabernet, a wider one for Pinot Noir, and a tighter rim for Sauvignon Blanc. They are heavier than Zalto but still impressively light, and the dishwasher-safe machine-blown crystal makes them survivable for everyday use. The Cabernet glass in particular is the practical standard for bold reds.
If you are buying for a gift, Zalto feels more special. If you are building a real home set for four to eight people, Riedel is usually the smarter first purchase.