For SchH a fursaver collar is what is used(in trials and in training)so no harness is used....the harness may be used in protection(the dog knows when the harness goes on what they will be doing) and for that I like the https://www.bridgeportequipment.com/ProductDetail.aspx?productId=96 even though the description is "tracking" it is a really good one for protection/bitework. Excellent quality for the cost.
If you are doing AKC style tracking, I'll leave that up to the experienced AKC people
If you're looking for a good quality harness for SAR work, you may want to look at the ones Signature K-9 in Virginia produces --> Nylon Harnesses
A lot of their harnesses are "multi use" and can be used for tracking, protection, etc. Most have velcro panels for ID labels (like a Velcro "Search and Rescue" label) or can have pouches/pockets added to them.
All their stuff is really well made, too. I have the Extreme Duty Harness they sell, as well as the breastplate adapter that makes it a Y-front harness, and like it a lot. It's really nice quality and being nylon, I can toss it in the wash if I want to. I've got some external pockets on it for carrying small items (keys, cell phone, etc.) on day hikes, too, and it works really well for that.
My only gripe with their gear is that it doesn't come in sizes. Ronja is really small in girth, so getting this to fit her right was a challenge. If you have a standard-sized German Shepherds, though, there should be no issues about fitting it.