Pressure-treated pine is the workhorse here, and cedar stays straighter over a 6 ft board. Solid fences hold snow against themselves, so the bottom board sits an inch or two off grade. Frost heave is the real enemy: a post carrying a solid panel has to sit below 48 in or the run goes wavy by its second spring.
Solid 6 ft cedar or pressure-treated pine, no gaps, stockade or board-on-board. Full coverage from grade up for overlooked yards, exposed decks, and pools. The most wind-loaded fence we build, so post depth carries the job.