I personally like the Apple Watch without a case. I think the Apple Watch is meant to be used as a watch and I don’t like those types of cases. Also, be aware that dirt/debris can get trapped inside those cases if not cleaned regularly, and can scratch the aluminum casing or display.
Also, just comparing those pictures, it looks like the display looks more muted with the case attached.
I have the same case you have on your watch. I am a printer technician for Xerox working on production level printers and have to put my arms in very tight areas with metal all around. Without the case I would have destroyed my Series 2 about a dozen times. On the weekends I'll remove the case and give it a quick cleaning before putting it back on.
Another vote for no case. I got a free case as part of a band I bought and ... all it did was collect dirt, grime, and dust - all I could think about was how it would damage the watch (but it was a cheap one with lots of exposed areas).
I use a clip-on case when Im working at the pub (cleaner/cellerman).
I'm shifting barrels and the like and the line cleaning chem is an acid. I don't want to splash that on my watch glass.
When I'm through I flip it off... no probs.
I don't mean to sound too harsh or disrespectful, but buying a protective case for your watch has got to be one of the silliest ideas I have ever heard of. Might just as well put a protective condom over your car. XXL size, of course.
Obviously its a personal choice and you can do what you like but there is no way I would ever put a case on a watch, to me it looks beyond bizarre. I wouldn't do it even if it meant my watch would get scuffed up for its lifespan but it is one of the reasons I bought a SBSS S3 because between the actual watch case material and the sapphire I don't have any marks at all.