Citizen Eco-Drive OnevsGrand Seiko SBGP009

The Citizen Eco-Drive One is widely celebrated for its groundbreaking thinness, with multiple sources confirming its status as the world's thinnest light-powered watch, measuring between 2.98mm and 3.5mm. Owners and reviewers alike praise its exceptional lightness, titanium construction, and good build quality that avoids feeling flimsy, noting its "wow factor" and superb finishing. The watch features a proprietary, ultra-thin Eco-Drive quartz movement and a synthetic sapphire dial, with some models offering up to 12 months of power reserve. However, its high price, ranging from $3,500 to $5,000, is a significant drawback for some, and its aesthetic is considered too plain or dated by a minority who prefer other Citizen models. The Citizen Eco-Drive One is also noted for lacking a seconds hand and having only splash-resistant water protection.

Grand Seiko SBGP009 owners note its "normal quartz" movement, and one owner criticizes the bracelet for lacking a taper. One owner cites a 40-year-old Seiko quartz watch that has only required battery changes as evidence of the reliability of Grand Seiko's quartz movements. On balance, owners value the Grand Seiko SBGP009 for its perceived long-term reliability.