Tissot Seastar 1000 Powermatic 80 GMTvsSinn U18

Owners widely praise the Tissot Seastar 1000 Powermatic 80 GMT for its excellent build quality, smooth winding feel, and the reliable Powermatic 80 movement providing an 80-hour power reserve. Reviewers highlight its remarkable value under $700, comfortable wearability, and appealing case/dial ratio. Some owners note the bezel's functionality for tracking a second time zone and the need to adjust the hour hand for date setting, a characteristic of its "True" GMT function. The rubber strap is considered comparable to those found on significantly more expensive watches. However, concerns exist regarding the movement's serviceability due to potential plastic components and reliance on Swatch Group service centers. Some find the bezel font and dial spacing unappealing, while others question the mineral glass bezel insert as a cost-cutting measure compared to ceramic. Accuracy is generally reported as good, though not COSC certified, and lume intensity is described as average by one owner.

The Sinn U18 is praised for its unique deep blue/green dial with three-dimensional oxygen bubbles that change with light, and its comfortable, easily adjustable bracelet. Owners find the watch stunning and a piece of history, appreciating the refined hands. The Sinn U18 features a 44mm, 15.5mm thick case made from German submarine steel, offering a 2000-meter dive specification and Sinn's Ar-Dehumidifying technology, powered by a Sellita SW300-1 movement. The case thickness is apparent, and the watch comes as a complete set with box and papers for $3,000-$3,680. On balance, owners and reviewers rate the Sinn U18 highly for its striking dial and robust build.