I don't remember chinos being a men's staple when Dockers released it's first.  Back then, Dockers wasn't owned by Levi's and their biggest competition was probably Bugle Boy.  Their first chino was casual and rugged, as chinos were meant to be, since they originated for military wear.

At some point over the next few years, as chinos grew in popularity and Levi's purchased Dockers, they began making them more dressy and with lighter fabrics.  The chino went from a rugged pant that was a step up from jeans, to a super casual option for business.  They went from a pant mostly worn by younger men, to a pant mostly worn by older men.

Why am I telling you this?  Because the Dockers Alpha pant is more like the original Dockers chino, that was more rugged and casual than what we now associate with the chino pant.  The Dockers Signature is the culmination of what the chino has become - i.e. lighter biz-casual pants made for older men, who may want to iron a crease down the middle of the leg.  In contrast, the Dockers Alpha is the pant you want to wear with boots, while foraging through the forest or anything that requires outdoor activity.

Nothing against biz-casual wear, but the dressy chino is just so mundane.  I love the Dockers Alpha and I find it shameful that the clothing industry has, for the most part, turned the chino into a dressy pant.  Hopefully Dockers will continue making the Alpha forever and offer new fits when necessary.  I've always preferred rugged chinos and always will, so while I might change my preference on the fit, it's unlikely that I'll ever prefer a more dressy chino.