From what I understand, link_to is used for get methods, and button_to is used for post methods.
On the other hand, I was told that with HTML5 semantics, <button> is used for any type of clickable...well, button. In the case I have a clickable button that sends a user to a form to fill out, should I create a button_to or a link_to?
It's simpler that you think.
That methods are Rails helpers and don't have anything to do with haml.
Yes, one method is for get and another for post methods. If you need to post any data to controller, use button_to (for example when deleting a record). Otherwise, link_to is enough.
Moreover, you can make link_to posting data using :method parameter:
= link_to "Something", some_path, :method => :post
Answering your question, use link_to.