My favorite is the Vietnam era coated nylon USGI poncho and liner. the nylon is thick enough not to blow around to much but thin and light enough to pack well. They were a big improvement over the rubberized version they replaced.

The OD green is easy on the eyes. The snaps are close enough together to work right, the grommets are sturdy, and the hood has a drawstring that works well. For hot/wet, semi-tropical conditions they work well. Often better than even the most expensive breathable fabric rain jackets and pants. when things are hot and wet there is just nothing that can replace ventilation.

Used to be I could get then from any number of sources for $10 to $15 each.

The liner adds considerable warmth and used with the poncho makes a useful sleeping bag for moderate weather. The Thinsulate or, newer fleece, versions are a step up from the old fiber-fill liners. The old fiber-fill ones used to go for $20.

Problem is that genuine USGI ponchos are hard to get. Those available are often in poor condition or cheap Chinese knock-offs. Now don't give up on all knock-offs some are very good copies of the USGI version with only the slightly off color or labels telling you the difference.