I have fired hundreds, if not thousands of 22lr through my GSG 1911. I use Remington 22 Thunderbolt, American Eagle, CI and Aguila with no function issues. Just make sure that you look for High Velocity on the box. Standard or low won't cycle a semi auto reliably.
You may also find that your GSG has a preference for a particular brand of ammo. This is not unusual. Some guns are a little picky, other don't care.
Start out with a couple hundred of each and see which yours likes best.

Ones that go bang !

CCI makes some of the most consistent and reliable .22lr ammo on the market. CCI Mini-mags have always worked well for me in semi-auto firearms.
budsgunshop.com/product_info.php/products_id/63200/cci+22+lr++40+gr+mini+mag+round+nose+0030+100+round+box

Anthony, both CCI and ELEY are equal in reliability and consistency : budsgunshop.com/product_info.php/products_id/713070304/eley+target+22+lr++40gr+50+pack ------------------- budsgunshop.com/product_info.php/products_id/35096/cci+select+precision+22+lr++40+grain+lead+round+nose

CCI mini mags are the best but they are out of stock at Buds but should be easy to find locally budsgunshop.com/product_info.php/products_id/63200/cci+22+lr++40+gr+mini+mag+round+nose+0030+100+round+box