What comes off as the most professional?

var hyphen-ation;
var under_score;
//or
var camelCase;

Either underscore or camel case. Just depends what mood I'm in on which one I use

as long as the code is conformant which usually means camelCase for classes and snake_case for configuration and dash-separation for service names In my case

I am guessing that you are using JavaScript and with that in mind use:
1. camelCase for variables that change
2. UPPER_CASE for variables that are constants
3. Capitalization for classes

P.S. you-cannot-use-hyphens in JavaScript variables

NEVER hyphenate.

hyphen ? that kebab case. var test-suite-1

Depends on the language. I know Python generally people use the underscore style, whereas Java camelCase is more appropriate.