Consider the tricks that <a href> knows by default but javascript linking won't do for you. On a decent website, anything that wants to behave as a link should implement these features one way or another. Namely:
Now if you don't want to simulate all that behaviour, I suggest to use <a href> and style it like a button, since the button itself is roughly a shape and a hover effect. I think if it's not semantically important to only have "the button and nothing else", <a href> is the way of the samurai. And if you worry about semantics and readability, you can also replace the button element when your document is ready(). It's clear and safe.