thats a hard question considering ther are so many diferent languages and tbh carolus seems pretty good but hes only just joined so i wont judge his skill befor i have seen more of his work
I suppose you could do it on how many sales you've made, but alot of people dont sell half the stuff they make because its either not great, or the application has already been made. You could also, say how much experience you have coding in a certain language.
This isn't really a fair question. Everybody is better at a certain language. Like Blessing, I know you are good at C#, but you may be lacking in PHP. It all depends.