Chatpad for the most part. If doing admin commands I copy/paste with the iOS Xbox app. Though even with the chatpad I still am SLOW at responding, so sorry about that ahead of time. LOL I prefer voice chat for doing extended conversations.
One thing I wish they'd do is add a bit more chatpad support into Ark, like say just being able to enter text into the text boxes rather than have the keyboard popup, whistle keys, etc.