Mid-weight hiking boots
Half a size up. The single most important thing you own.
What to look for: Waterproof membrane, ankle support, stiff-ish midsole, half a size larger than your street shoe
Feet swell at altitude and on long descents your toes need room, or you lose toenails coming down from Kala Patthar. Ankle support and a stiff midsole matter on rocky descent more than on the way up.
Skip the heavy mountaineering boot unless you are climbing a peak. It is more boot than a teahouse trek needs and your legs feel every gram.