Seagate and Western Digital are comparable. Manufacturers such as Hitachi, Samsung, and Toshiba generally have limited models or only focus on notebook hard drives. For example, the more classic model in the past two years was 500G single disk 16M. Seagate Western Digital has its own hard drive with this specification, but other manufacturers do not. Hitachi's 500G is equipped with two discs, which is much inferior in reading speed, and there is no advantage in price. So I say there are only two leaders in mechanical hard drives, Seagate and Western Digital.