Agree Link would be a good choice since there is integration built-in and it comes free with PS. 

However, you will have to sacrifice some control and you must be ready to help clients diagnose login/access problems, which pop up from time to time, largely due to deficiency and as a result of Support not being very knowledgeable about the product themselves.  You can search this board and you will see that there is no lack of questions and complaints about Link.

Another choice is to use your own secure client portal.  You will have much more control over these portals and they tend to be more user-friendly, except there will be no integration with PS.

To use Link, you need to be very familiar with the entire workflow.  If you haven't used it, set yourself up as both the accountant and taxpayer (with different email addresses).  Test out the end-to-end process, discover the kinks, and beware of possible solutions.  Reading the help articles and discussions that have been raised here would also help.