If you're like everybody else I know, the shed space we have isn't typically the shed space we would want to have if money was no object. They're always "too small", and too limiting in accessibility, approaches not planned as good as we'd have liked, posts in the way, doors not big enough, etc.
If it's just for equipment storage, and not every day use, so you don't really require electric assisted operation, single piece roll across regular old machine shed door will be the lowest cost, and will give you the greatest opportunity for the tallest (and widest) opening (if its on the gable end of a trussed building, no head room or header required). If you want "electric assist", then "garage doors" (typically called "overhead doors", that store horizontally on a track hung below the rafters/ceiling when open), or the roll ups (that roll up into a coil right above the opening) will be more weather/air tight, but will cost more and generally will require at least 12" of head space below the ceiling/bottom of truss (12' shed to bottom of rafters, maximum of an 11' door opening clearance)... unless you can put that required headroom above the bottom line of the rafters??? (roll up doors can most easily make this work) Sounds like your width is already defined by posts (bays?), but I would "avoid" going as narrow as 14', unless I didn't have a choice. 16' you can fit two car/pickups into side by side just barely. The narrower the opening, the more likely it is that it'll be too narrow for "something"... and perhaps more importantly, the more likely you are then to hook something on your door frame.