Seagate's barracuda range are their most widespread, and also their cheapest model. I have several decade-old seagate drives here, none of which have stopped working yet. (albeit under light load). I have no experience with their (or any) SSHDs.
WD's product stack goes Blue-Black-Red-Purple (I think). There is also a 'Green' model which is supposedly more eco-friendly. The Blue model is the entry-level model, the black is the high-end consumer model, the red drives are for nas use (lots of drives in a compact environment) and the purples are for surveillance servers (24/7 writes with maximum endurance)