What do hiring managers want to hear when they ask my why I am leaving my current position?

This one of the top 5 dumb, repetitious questions that don't matter. Are you leaving because you have outgrown the position and need a challenge? Tell them. Don't make it about compensation or benefits. Are you ready for the next step in your career? Do you want to make a difference? Make it about the company (due diligence) This company has something your current company does not.

They don't want to hear the truth people leave in a perfect world so just make up a lie and sound positive

Growth statements

Something that relates back to their company i.e. refer to an element in their company culture or a specific project they're working on. Don't be negative about your current employer. Instead mention opportunities for growth, learning new things, bringing your expertise on something to their company, etc. Unless you're leaving because of downsizing or something like that or if you're searching for more stable employment or full - time vs part - time / days vs shift work or the like, you could mention that. Nonetheless, always try to frame it about them and what you can do to help them meet or exceed their bottom line / meet their goals, etc.

The truth. They want to know if there are problems so that they can fix them and get constructive input on their company.

Ideally, they want to hear that you’d rather work for their company than your previous one because it shows you have skin in the game besides a paycheck. This can backfire though as they may think you’ll work for less if you really love their company. You could spin you decision around wanting to do what’s best for your former company but getting too much pushback, rather than simply “I didn’t like my job.”

“I’m looking for a greater challenge.” Nothing negative about the prior company or management.

Because I believe the opportunity you are offering is far more promising than my current state.

Basically they need to know if it is something they can prevent from happening to the next person or even you. If they can change the scene, they might just try to do that if you're a worthy employee.

I’m looking to advance and there’s no room to do so where I am. I hear “I’m a go getter and willing to work to further my career” I’m hiring you.

I found a new job. So that why they think that they are not at fault. Also check your grammar on this question as you have a typo. (ask my why)

That you are looking to move up or expand your knowledge and experience or that you really love their company and can't pass up an opportunity to work there

To better yourself by expanding your experiences

We want to hear the truth. We're looking for whether there are factors also present in our office that would make you unhappy there as well. We want to hear about what type of work you want to be doing. Basically, we want to hear about what things are deal breakers for you that might not otherwise come up in the interview.

The truth. Even if it’s difficult to say, or to hear. It’s the only way to make things better for all.

I'm not sure what they want to hear. But, it's probably related to bad pay and worse management.

To be part of a company that I can grow with

How they can improve...salary? environment? boss? culture? diversity?