I like both but I notice languages that use camelCasing for members sometimes need more adjustments when you want to edit your code. For example (in Python):
node.customData()
vs
node.setCustomData()
custom changes casing. It could be avoided if it was:
node.getCustomData()
In C# they will use PascalCasing for example.
I know some even use no casing so:
node.getcustomdata()
It seems to be that scripting languages generally prefer camelCasing more than PascalCasing to be more relaxed?
Is there a reason for choosing one over the other from a programming language design POV?