modern IDEs usually make the _ as a prefix useless. unless you develope with emacs or VIM, but I would expect the old tabs vs spaces question then.
In the end define the coding style you want and stick to it, that's the only thing that matters ... the "look and structure" of code is nothing more than an opinion and opinions are like assholes ... everyone got one :) .....
i come from the c world we used to separate functions with "_", everything is singular and lower case the java people like their camel case ... the interpreter does not care and should not care at all as long as the instructions come in, in the right order .....
the longer you code the more conventions you had and the less you care :) define it, lint it ... fuck it ;)