>>27273901. Bug bivy. Good option. Cheap. Tarps don’t have much protection from splashes or wind driven rain. Tricky setup, comparatively. Most ventilation.
2. Just a bivy; “bivy sack” is redundant. Least versatile. It has a single use; lying down for rain and wind protection. You’ll have to eat in the rain. Really only used by larpers and serious mountaineers. Whatever humidity is trapped inside with you will absolutely condense when the temperature drops.
3. Not a bivy. That’s a tent. The entrance is on the front rather than the side. This style of tent has fallen out of favor due to less vestibule space, tricky entrance, and less ventilation. They can be lighter though, which is why ultralight brands like Tarptent make them.
4. Most popular for a reason. Not as much ventilation as the tarp, but much easier to set up with more wind and rain protection. Better ventilation than a bivy or a front entry tent, with way more usability than a bivy.
I wouldn’t consider a bivy to be an option. You will absolutely have nights, evenings, and mornings with rain. With any kind of tent or tarp, you can eat, check maps, take care of your feet, organize your pack, masturbate, read, or whatever. In a bivy you can just lie down and wait.
There’s nothing more cozy than chilling out in a tent, eating or reading in the vestibule, wrapped in a quilt, with rain pattering against your tarp. Hammocks win that one, but a bivy isn’t even in the contest.