I have been in the Shoe Repair industry for 20 years now and the products I have found to be great are as follows. 1) Collonil waterstop colours. The boutique polish which keeps the leather waterproofed and nourished. Most common  colours and neutral. 2) Good old fashioned Joseph Lyddy (Dubbin) You also can use these products for leather bags & jackets.   Stay away from Kiwi it dries out the leather and then the leather starts to crack.