My rain kit depends on the location. For the AZT it was a disposable poncho, Cosowe brand from Amazon, with sleeves. Surprisingly durable. I bought a 5-pack with the idea that I could go through a bunch of them for less weight and less cost than a rain jacket. I’m still on the first one. I only experienced one real storm where I needed to wear it. The only thing I didn’t like was I couldn’t get it on over my pack when I was out on the trail. I could do it at home but not on the trail.
For the CDT Wyoming section it was a vinyl poncho, until after a few storms it tore and I replaced it with a Frogg Toggs poncho, which didn’t cover me very well and also tore the first time wearing it.
My next attempt at rain protection for the CO CDT will be an Exped Pack Poncho UL. It is closed down the sides, has longer sleeves than a normal poncho, has an expandable pack bulge, and has a snap between the legs so it’s not so flappy.