It doesn't really matter, its personal preference for what hard oils (butters) you use and how much of each one. With whipped body butters for myself I frequently just go with what I feel like, or what supplies I've currently gotten. When I make whipped body butters I start with thirds, 1/3 soft oil, 1/3 coconut oil, and 1/3 hard oil. Then go from there as I'm whipping it if I want to add a little more of anything. I use really light fast absorbing soft oils so it absorbs quickly.
I don't melt down what I don't have to, which speeds up the process and can help with issues such as shea becoming gritty. Shea, mango, coconut oil don't need to be melted down. Cocoa butter is super hard and does, etc.