I am sorry for this delayed reply to your gardening question. We are transitioning to a new Q&A system and your question was unfortunately lost in the transition. I have discovered it now and hope this reply is not too late to be of help.
Barberry is fine as is Indian Hawthorne. For a fine textured plant such as the ones you are removing, try one of the low growing or prostrate types of juniper. Even upright types can be pruned to very formal topiary forms.
Thanks for the question. Please stop in again soon!
Q&A Library Searching Tips