These are dive watches so they are water resistant for up to 200m. Other neat features include a uni-directional rotating elapsed timing bezel, a day/date calendar (in English and Kanji), and LumiBrite hands and markers for better visibility. The automatic movement provides a 41-hour power reserve.
In terms of which is best, the brown fits the turtle shell aesthetic best, but the blue dial just simply looks the freshest. Turquoise will likely be a popular choice for many, however.
These watches are available in November on Seiko’s US site and retailers for $750 USD.