which is it in your opinion? DBC seems to be the most famous, but are there as reliable and cheaper alternative around ? And others to avoid like the plague, like UNG for tracking natural gas ?
There are many broad basket commodity ETF's such as DJP, RJI, GSG as well as dozens of commodity specific ETF's (like UNG). There is no one best, although UNG as you mentioned is one of the worst, if not the absolute worst.