I have been doing some analysis on the value of a tick or the cost and advantages/disadvantages of buying at the bid and selling at the ask. I wanted to find out which instruments had the "cheapest" and most "expensive" ticks to trade. Below you will see that ES, S&P 500 futures are the worst when it comes to getting value for the ticks you accumulate.
file link spread analysis
Just look at ticks per range values, if you enter at the market it is only going to cost you $10 to theoretically or potentially gain 200 ticks (average daily range over the last 20 trading days). Compare that with a 25% more expensive tick of the ES at $12.50 and your potential is only 80 said ticks. I would argue that oil is 3 times more advantageous to trade (especially if you hop on trend and ride them with Mega Bars!).
NQ and YM are way better to trade if you want to mix your trading in with some index trading. My suggestion is to stay away from the ES all together.
Why is ES so hard to trade? Expensive ticks. Limited range. Too efficient (hard to gain an edge). In the ES you are competing against prop firms, hedge funds, HFTs and the FED of course.
You may say but ES is so liquid! Yes it is BUT if you are not using that liquidity it is actually hurting or at least not helping you. You can sit a long time waiting for your 1-2 contracts limit to get filled while there are thousands of traders and computers ahead of your order.