With higher watts i wouldn't worry about subohm to much. There are plenty of cloudheads that will say its better, but surface area is key with proper airflow and wicking. That being said standard microcoil a standard ohm (like 1.2 for example) could give more vapor then a .3ohm microcoil as their is more surface area. As long as you have enough airflow to accommodate the extra vapor being produced.
When you get into the fancy twisted clapton hurricanes blahblah stuff then can't really say as i preffer micros so far.