I too have the Tough Armor (it's hard for us Brits to spell armour without the u!). It has a built in screen protector, it does add some bulk to the watch and the crown it a little more tricky to use.
I work as an engineer and initially bought the 42mm Space Grey Sport, I didn't use a case and the screen (IonX) got scratched within a month, bummer. I then sold that one and bought a 42mm SS W BSB. I use this case Monday to Friday to prevent any knocks and scrapes damaging my new watch. I like this case for 2 reasons, firstly the protection is great all round, secondly is disguises the fact it's an Apple watch. This is good for me as I work in some very dubious areas and don't really want to advertise what's on my arm. I wouldn't wear it out in the evening or at weekends but for anyone with a rough job this is brilliant.