Nutritionally speaking it's best to use a range of suitable fats - lard/dripping, coconut oil, butter or ghee, extra virgin olive oil (which is best combined 50:50 with butter). I don't believe that would make a huge difference to weight loss tho'. More variety might help you eat a bit less fat?
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.