They are ECO drives (5400rpm) but not in use too often
Having storage modules bolted into the MOBO is IMO not a good idea -- means if the storage device FAILS you have to chuck the whole machine away (and there's enough junk littering the planet these days --we need to use resources much more environmentally).
Also you might want to try out different OS'es, move data between machines or even REMOVE the device altogether for security.
"Flashing" Rom's is not for the faint hearted either. Fixed storage might superficially have attractions but it's not very practicable and I'm sure will only be used in things that have a built in OS or "embedded OS" say like POS gear in Supermarkets etc). But again these types of applications don't need mega fast storage anyway -- It's no good if the Supermarket till gives you your total bill in 0.1 NANOSECS if it STILL takes you several minutes to bag up your purchases and load them into the trolley to take them away.
Most of the issue is price so if anyone can get past that I don't see any advantage now days for using hdd's for anything 5200 or 7200 ssd's are better and create less heat,
Brands well that is a toss up
I like crucial but most people like Samsung's.