We only use the EK brand collars on ours for those that have snaps (Dante, Akira, Audrey), or ones with metal buckles. The cheap plastic clips break. I've used these collars for YEARS on shepherds and they are very very heavy duty snaps.
ex: EK Ekcessories Medium Mutt Adjustable Dog Collars at PETCO
We use the large size on adult shepherds, even small adults like Audrey although the mediums are technically long enough. I prefer the bigger snap.
Either way, we don't walk our dogs on their flat collars - they are strictly there for ID purposes.
I don't really care for the buckle collars because the end always ends up looking ratty and doesn't lay flat. If you get it two inches shorter, it's too short to poke back through the tab and stay there, and if it's two inches longer it sticks out too much and looks unkempt. I like the snap collars because you can adjust to the micro-inch, but I will only use the EK ones because I don't trust the cheap ones.