I estimate that the mane 6 from most to least money made is Rarity, Applejack, Rainbow Dash, Pinkie Pie, Twilight Sparkle, Fluttershy. This is just my guess it might not be correct.
My favourite merchandise is the figures, at the moment I have 10 little figures but I'm hoping to buy some funko vinyl figures when I find a shop that sells some. There's a pop culture shop opening in a week in my local shopping centre so I'm hoping they might sell them when they open.