How to choose grips for trail riding AND commuting?
I use Oury Mountain Grips on my mountain bike and my city bike. 

They have a cheaper slide on version (about $10-12 USD) and a lock on version ($ about $30 USD) which I prefer.  The lock on version avoids the 'slippy grip' issues you sometimes have when water eeks under the edge of the grip and it slips on the bars.

These grips are smooth and cushy enough to wear without gloves and are good and sticky when used with gloves.