Ultimately, the best material you can choose is the one that works with your extension or with your underground drainage system. Whatever type of drainage system you’re putting in, whether it’s corrugated or PVC pipe, use the product it’s intended for. PVC is probably the most durable on the market and black corrugated pipe is the most universal.
When connecting a corrugated flex pipe adapter to a metal downspout, in addition to slipping it over the downspout, is it better to glue or screw it on in order to anchor the two components together?