If you are looking for an easy way to annotate PDFs, keeps Stamps in mind. For example, in PDF Expert, you can create custom stamps with any combination of words you regularly use. By simply holding your finger on any area of the page, you will raise the stamp menu so that you can select the phrase you are looking to use. Each stamp can be dated and timed if you choose.
A very helpful summary of apps for judges and lawyers:
This link contains the The National Judicial College iPlugworking list of apps which have been discussed (but not necessarily vetted)