What futures contracts have the most volatility relative to cost/margin requiements? Any contracts, not just commodities.
You can get a table like the one below and look at the change column. https://www.dormantrading.com/trading-resources/most-active/
You can try to find some discount broker, that allows you to trade FDAX for some very low margin. That will be fun.
Volatility occurs when price is uncertain. This isn't a constant. But some commodities exhibit volatility due to periodic demand/supply variations. That being said, Nasdaq behaves like a drunk child because it is made up of growth stocks which have no accepted value.