Airline hose of whatever variety you prefer.
Reinforced clear stuff is OK, but oils will cause it to eventually go brittle/weaken, and daylight can cause it to perish. Typical black rubber hose is more durable, but needs more clamping force. There are more fancy hose types, but not really worth it unless you have money to burn to make things look pretty.

Pigtail fittings. They should be a tight(ish) fit in the hose. If they drop in to the hose with little effort, they're too small. They should take a bit of effort to push into the hose. If they simply drop in, you're to struggle getting the crimp tight enough to stay on and seal.

Oetiker/O/Ear clips.
Exact name depends on supplier, but a search for Oetiker clip, will show up the basic one with two opposing crimp points, or the slighter more complex one with a single crimp point.
The banded type with the single crimp point do provide a better crimp, as they avoid the hose bunching up under the crimp point(s).
You need whatever size is a tight fit before crimping. If the clip is rattling around on the hose before crimping, it'll likely not crimp tight enough, and quickly/eventually blow off, depending on exactly how loose the crimp is.
You can use generic hose clips, but they're a pain on hoses you're handling regularly, as they nearly always catch your hands.

Oetiker crimp pliers. They can be done with generic side cutters, but they're not ideal as they don't crimp parallel. A set of end cutting pliers/pincers work, but you don't want a set that are too sharp.


Off course, the other option are proper hose swage crimps, but then you're into needing a proper swaging machine with suitable dies.