butter substitute?

Hi peeps,
im trying to plan my xmas baking and cooking. one of my old recipes (banana bread) im trying to transform it to suit slimming world and make it as syn free as possible.

what is a good substitute for butter?? any suggestions and what about plain flour? is rice flour or any other varieties better?

please help!!

There are things called butter buds which were discussed a while ago on here.
http://www.minimins.com/slimming-world/62422-butter-buds.html

Not sure what they would be like used in cooking though.
Me and Toe picked some up when we went bluewater last week but i am yet to try them!