Smoking wood used for Beef?

Oak, mesquite, apple - kind of depends on what's available locally. Where are you?

I grilled a prime rib chop over apple, came out great. The meat was so tender, smoking may have introduced more flavor but I didn't want to risk it on a $40 steak.

The chop was about 3 inch thick, cooked it about 12 min per side for med rare inside.