What is the cheapest futures contract to trade?

Hello there, I'm curious about futures trading and I'm on the lookout for the most affordable options. Could you please explain to me what exactly is the cheapest futures contract to trade in the current market? Are there any specific factors that I should consider when choosing the cheapest contract, such as liquidity, risk, and the underlying asset? Additionally, could you provide some insights on how to evaluate the cost-effectiveness of a futures contract and if there are any hidden fees or charges that I should be aware of? Thank you for your time and assistance.