I’m not a guide dog user but during my training as an orientation and mobility specialist I had the opportunity to visit The Seeing Eye. They work with you to find the dog that works best with you. I’m going to be honest and let you know that I walked with a lab and then a German Shepherd and the shepherd was much much stronger. They’re not going to place you with a dog that moves too fast, is hard for you to control, or doesn’t match your lifestyle. While it would be worth mentioning that you want a specific breed I would suggest that if you do go to the school you remain open minded to finding the dog that suits you best. Good luck!

Some schools do only certain breeds. They also try to match you to dogs with certain characteristics (speed, size, etc).

You can apply to multiple schools, but also be aware that each school has their own requirements as well.

I applied ages ago and I have my third dog now. I did a lot of research and had a couple places I wanted and applied one at a time. All my dogs are from The Seeing Eye and if you want a shepherd, they're the place you want to go. For general info about the process, Guide Dogs for the Blind used to have a good FAQ about it and that's worth checking out. You can also just call the schools and someone can talk to you. Good luck!

German shepherds aren’t the best choice guide breed for most people which is why most schools no longer use them. They have shorter average working careers, can be overly sensitive and easily stressed, and many not bond with more than one person ie. they may not accept family members as non-strangers. I have known good shepherd guides but you should be very sure you know what you are getting before considering this type of dog. As is this is your first dog I would also suggest perhaps considering one of the larger schools that can offer more post graduation support. This can be a big factor in your ultimate success with a guide. The schools have changed and improved a lot over the last 25 years and the differences between them are smaller. You aren’t going to find big differences in training methods or approach except perhaps at the tiny schools.

Talk to the schools and continue talking to other handlers before you decide. The more you know beforehand the better your chances.

I applied and graduated from Guide Dogs for the Blind and didn't really care what kind of dog I was paired with. I was paired with a fantastic Golden Retriever and if I ever apply for another one, I would highly prefer another one. There tempermetns are great in my opinion. I know that GDB doesn't train German Sheps anymore and I heard that was due to aggresion issues with certain dogs that graduated. I do know that Seeing Eye still trains them, and they are a very respected organization. I had a teacher back at one of my rehab schools that refused to go anywhere but Seeing Eye and had several dogs from there. As others have said, the breeds will have different temperaments and some might suit your needs better than others. It also will likely increase the wait times drastically if you specify a certain breed, though I'm not certain if any school will guarantee a certain breed if requested.
I would also consider which school is closest to you. It's probably not the biggest deal, but it's pretty convenient to be close to your school if you ever need veterinary services, etc.
Also, this is just something I've wondered about, I mean no offense by it, but I'm curious if German Sheps would be refused service more or less frequently than say labs or especially Goldens. Goldens are known as one of the friendliest breeds out there and Sheps have a bit of a bad reputation. So I wonder if there's any issue with the publics perception of them at all.

I am currently working a dog from Southeastern a yellow lab, currently have a application in with pilot, looking at Eye Dog Foundation in Arizona they do all German shepherds their waitlist is a bit long about a year. Also looking at gallon parts out of Mississippi they do German shepherd's, Doberman pincher's.golden retrievers and boxers. They are in-home training like for Delco Guide Dogs.

Fidelco in CT is a Shepard only school that also travels to you, if you're firmly set on the breed.

That said, though, please think long and hard about this. Shepards can be very protective, even aggressive, if people get too close to their owners/handlers. Friends have had their guide dogs body people out of the way, which... can be problematic. If you live with other people, or if you don't get out just about every day, a Shepard might not be for you.

I was paired with a lab/Bernese mountain dog! His name is Gumbo and he's the bestest boi. Are you sure you only want a German Shepard, what if you vibe really good with another breed?

I applied at Leaderdogs in Michigan and Southeastern in Florida. Decided to go with Leaderdogs. Once they had all required documents, it took maybe four months. I ultimately based my decision on factors of research, word of mouth from O&M instructors and, to a lesser extent, because they got back to me quicker.
I elected not to have a preference in breed, as what I wanted was to be paired with The best possible option as seen by the trainers.
Ended up with a medium-sized black lab.
I have nothing but good things to say about my experience at Leaderdogs. Staff was lovely, trainers were excellent, comfy and nice lodging.
Being from Florida, I thought it was a real treat to do mobility in Michigan during winter. It was also nice meeting and getting to know a bunch of other dog handler’s over the training period of about just over three weeks. I made some friends whom I still keep in contact with. It was, all in all, a very lovely experience.
That being said...

Having a guide dog is a major responsibility. You have to work them often to keep their skills sharp, exercise their bodies and stimulate their brains to keep them healthy and happy. Hygiene maintenance is also super important.
But if you’re up to the task, it’s an experience unlike any other. I love my little guide to pieces and he is very good at what he does.

I applied to one school and in the process of applying to a second one. I was told to apply to multiple schools as some of them have a waiting list. If you're in North America then consider CNIB (Canada), Guide Dogs for the Blind (California, USA), Mira Foundation (Canada), Lions Foundation (Canada). There are few more in the US but I don't know them as I'm in Canada. The Mira Foundation has dogs of different breeds other than Labrador Retriever and Golden Retriever (and mix of the two). If you're in Europe, German Shepards are possible. That's a widely used breed there.