I know several that come to the dog daycare where I work. Of the 10 or so that I know best, there's enormous size variation, from a very petite female who's maybe 40 pounds and whose shoulder comes to just above my knee, up to a gigantic and frankly very overweight male who weighs somewhere in the neighborhood of 130 pounds and is about waist-high. I don't know any calm or non-neurotic GSDs, but keep in mind the environment where I meet them selects for specific needs- people whose dogs happily sleep all day don’t typically seek out daycare.
The shepherds I know are always watching and always ready to intervene. Well-raised and stable ones intervene by coming to get me and have me deal with the problem. Less polite ones will just dive in and handle it themselves, or try to. This is a pretty typical thing with herding breeds and can be a dividing line on whether or not someone gets along with a particular breed. Some people are charmed by a dog that thinks for itself and some people don’t like to be bossed around by a willful pet.
My experience has been that daycare isn't a great fit for most shepherds because they need more structured tasks than I can provide in this setting and they’ll eventually start amusing themselves by digging, barking, etc. Someone else addressed that point while I was typing this and it’s a good point- please don’t overlook the commitment of time, exercise, and structure they need.
They do attach to their people very strongly. They love their families tremendously, but the ones that spend a lot of time in daycare or boarding will pick a Designated Human from among the staff. That petite female I mentioned can jump all of our interior fences (6 feet) and will do so to get to our office manager, who she adores. We also have a shepherd/malinois mix named Trouble who is the most approval-seeking animal I've ever met, but easily bored. She amuses herself by harassing other dogs so I spend a lot of time "managing" her so she is doing pointless tasks to earn praise instead. Like most dogs they take their cues from the person they’re with- if you’re calm and confident vs nervous and jumpy, you’ll really see it reflected in how the dog behaves around you. And if you don’t set boundaries they can trample you. We have another shepherd whose owner didn’t work on walking nicely on leash when her puppy was small. Now that she’s grown, she pulls that woman around like a kite on a string. Apparently she also steals food off the kitchen table and does other naughty things because she’s never had anything resembling a boundary set for her.
Grooming varies tremendously as well. There are several distinct coat types and I'm told climate will impact it as well. Here in Texas they don't grow as heavy an undercoat, but it's still significant. When I blow-dry a shepherd I feel like I'm in a snow globe as all the loose hair comes out and blows around. There's also a long-haired variety which is less common. The only long haired one I see regularly also has a lot of joint problems (unrelated to his coat)- he needed hip surgery before his 1st birthday and gets a mandatory "naptime" every hour or so because he will continue running and playing even as his limp gets visibly worse. He has to be kept super thin to keep stress off his hips and knees, and I think a lot of shepherds would benefit from being on the trim side for this reason. That’s a big part of why people keep emphasizing finding a good breeder in this thread- SO many shepherds have bad hips in the US. It’s not uncommon to see pups marketed as having European bloodlines because they’re supposed to be better in many ways. *again someone addressed this while I was typing. Maybe... maybe my post should be shorter?
Anyway, I love the look and really enjoy the ones I get to hang out with at work but they’re just not a good fit for my life or what I’d like in a dog. It’s definitely worth significant thought before getting one. Good on you for researching!