I used to take sodium ascorbate and buffered C (from Thorne), but found that straight ascorbic acid provides much more of a 'kick' for me. It seems to be better for acidifying my gut, which is way too alkaline and filled with candida.
After looking online it was interesting to see that the late Dr. Cathcart stated the same thing--said that straight ascorbic acid is the main one he recommends for bowel tolerance C.