I'd have to say that I don't think the two are mutually exclusive.
Frequently the style of writing is determined by the purpose / need, ie; a formal business document will likely be more credible if written from the head, more than the heart. And, vice versa in the case of a novel, or a sales letter for example, where emotion is the key driver.
A good writer should be able to adapt their style and tone accordingly.
I personally find 'passion' an over-used attribute that many writers bestow upon themselves, and to me, this creates a pretension I find cringeworthy. But, that's just my opinion, not meant to offend.
But in fact, my main reason for responding to your question is because I read your comment that "My lack of a college education has held me back from pursuing my dreams of writing".
Don't let it SheliaKay. I left school at age 16, never took any further formal instruction, and made my living in advertising, writing business strategies, and as a copywriter.
Writing is simply using words to communicate. (Don't laugh, some people draw, some take photographs, it's all communication, and personal expression). You'll have your own style, and if you're passionate (the word belongs in this context) about what you want to communicate, that will bring your thoughts and words off the page and into the heart and mind of your readers.
As Nike used to say "Just do it."
Cheers, and good luck.