NQ or ES for your evaluation?
The two contracts
ES is the E-mini S&P 500 future: $50 per point, $12.50 per tick (0.25 point). NQ is the E-mini Nasdaq-100 future: $20 per point, $5 per tick. Their micros, MES and MNQ, are one tenth of that: $5 and $2 per point.
Both trade almost around the clock, with most of the volume during the US session. At Demos you can trade all four, on live market data.
Volatility
NQ moves more points in a day than ES, and its dollar swings per contract are usually larger. ES moves fewer points, but each point is worth more. In practice a one-contract trade in NQ carries more dollar risk than the same trade in ES for most intraday setups.
Neither is better. NQ gives more range to work with and asks for tighter discipline. ES is steadier and forgives a late entry more often.
Sizing next to the drawdown
Start from the drawdown, not from the contract. On a 50K with a $2,000 max drawdown, a loss of $200 per trade leaves room for ten bad trades in a row. With micros you can set that precisely: two MNQ at a 50-point stop risk $200, four MES at a 10-point stop risk $200.
The limit on a 50K is 3 minis or 30 micros. Few traders need it during an evaluation. Size for the drawdown first, for the target second.
Hours
The US cash session runs from 9:30 am to 4:00 pm ET. The open and the last hour carry most of the volume and the cleanest moves. Positions on evaluation and funded accounts have to be closed by 4:59 pm ET, so plan the day around that.
Pick one contract, learn its rhythm, and switch only once your results are stable. The rules are the same on both: Rules & FAQ.