Not for long, YM will soon move to Globex. Liquity will no doubt increase. And you will ony pay 1pt spread rather than 2.5pts on ES.
the spread may be tighter on YM but the liquidity (and hence the potential overall) is far inferior than the ES. 50 lots usually wont make a dent if you want to hit the bid or offer (on ES). We will have to see how the YM improves when its moved to Globex, cause the CBOT is unrealiable at best.
The YM is a piece of crap. The less liquid e-mini of the four and the worse exchange, regardless of the merge. I don't see what YM can provide that cannot be found in either NQ ES or ER2. Anek