I suggest that you use D-TRUST, since it is a German provider (your country), it is listed in Adobe Approved trust list and it is installed as trusted root certificate in Windows.
Basically I suggest to follow theese rules:
- use local certificate authority that provides digital signature certificates that are legally valid in your country
- use personal digital signature certificate that is linked with your name (they can also offer system certificates etc.)
- use a certification authority that uses pre-installed root certificate - check Adobe Approved trust list and Windows Cert Store.
You can check Adobe trusted root authorities directly in Adobe Reader here (only Czech language...):
Settings - Signatures - Identities and trusted certificates - ...
In Windows check this - but Windows trusted certificates must not be automatically trusted by AR, check this thread: