Some of many pianists I like to hear not only playing but also talking are Brendel (e.g. in his book 'Thinking about music'), Schiff (e.g. on the Beethoven sonatas), and Hamelin. In general, I think by far the majority of pianists have very interesting things to share, so I would actually like to hear more from them.
One pianist I don't enjoy to hear talking is Helene Grimaud -- the last couple of times I saw her, it was almost completely about her damn wolves mixed with some pseudo-philosophic statements...