Assuming you haven't built yet...
Given the north is mostly hilly, you will likely have a sloped site. While you can grade for a flat spot, I would go with a basement for a number of reasons: you are already digging out most of your depth, especially on a hill, so you will get relatively inexpensive space for the effort. Depending on the slope, you may be able to have windows and actually have living space on the lower level. Or a place to put the ski equipment...
Proper grading and waterproofing the exterior of the walls will elimnate water issues.
Like you seem to have realized, a slab is hard to insulate, plumbing is difficult to work on or extend for additions, and the floor is harder than a wood floor (less resilient.) Alos, if you raise the first floo above the grade a bit, you do not have to go as far down for the lower slab, and may be able to have your upper footings directly at the slab, stepping down as you approach the downhill side.
If you are looking at ICF's, look at Durisol blocks, made with recycled wood waste and cement. They have a high-R system, stackable, are not a petroleum based product, can be screwed into directly for finish or stuccoed. They assemble like ICF's but are easier ot work with. http://www.durisolbuild.com/.
Have fun!
Don