any ideas as to what breed would be a good choice as a companion for a german shepherd, medium sized dog out of choice?

We have a GSD and standard wire dachshunds.   They all get on really well together.  Often see GSDs and dachsies together

I often see them paired up with Yorkies.  Have been told by those who won both breeds that they are not over keen on border collies and the eye that collies give is often viewed as a challenge, and tyhey don't like the fizziness of the collies.

Being a GSD/BC owner for a mere 35 years my GSDs never had any problem with my BCs which came after we had the GSDs & all my BC's were working bred & had lots of eye, in fact my current GSDs is missing my last two BCs(they both died last year) dreadfully despite having the cavaliers to play with & keep her company

Lots of GSD people have Cavaliers with their GSDs & vica versa as well as GSDs with BCs with no problem at all.

It very much depends on the dog you already have, I have a friend who did have Border Terriers with her GSDs until the last GSD passed away

Both my GSD's are not too keen on BC's!  They do however get on with most other breeds, and live with two BSD's and a SBT very happily.

Sarah.

I have a gsd with collies and shes fine, i think its what ever breed suits your lifestyle is the one you should get.