Generally speaking, the marriage record is the one most likely to be correct, as the parents were named by the bride herself. In the death record, the parents are named by somebody else - surviving spouse or children, perhaps?
However, this is not always true. Tanner and Sawner are not so very different, when you allow for transcription errors, handwriting interpretation, etc. Have you seen the original records in each case? If not, I would suggest that would be the first thing to do.
The records at familysearch give the name as Breeden rather than Breeding, and the death in 1860, rather than the marriage.
You say you have only found the death record recently, the marriage c 15 years or so ago. I would perhaps concentrate on the names given at death for a bit longer, see what turns up.
Margaret
Edited: When you are ready to put your information in Wikitree, Susannah already has a profile here, Tanner-430. Profile manager still active, perhaps you could contact him and share information?