For my case, they only checked ID's, passport and PR card.
But guys, bring whatever you want in addition to the above to the interview if that makes you feel more at ease. It's better to bring extra than not bring enough.
For me they asked for - Kitchener office:
1- Prove that I am still working at my company, so I showed my company badge (my company's credentials).
2- My passport and my son's passport
3- land papers
4- The original IELTS (although it was allowed until last year to use the previous examination test, in which the original test result document was sent to the PR process as requested). Here I would have a problem if I had not done the test twice to show an original test result for them. They accepted the original that I did not use in my citizenship process, because in my citizenship process, I had sent a copy of the same exam result sent in the PR process. Now, at least in my office (Kitchener), they are asking to see an original for the language proficiency test, although it was different from what I added together in my submitted documents to start the citizenship process.