Earlier quoted context omitted.
Its quite rare for beef cattle to be 100% range raised. Beef cattle generally start out in rangeland or pasture where they eat grass with supplementary grain feed for a year or so. Then they get moved to an extremely dense feedlot or Concentrated Animal Feeding Operation where they are fed mostly grain based feed for the next 6 months or so.
That's what gives cows the taste most consumers recognize as "prime beef". Eating solely grass-feed is definitely a different taste;I'm not sure most consumers would like it, at least initially (outside of a hamburger).
Aaron Franklin talks about this in his book and mentions he only uses grain fed beef for BBQ. Grass fed briskets just aren't as tasty and lack the marbling of a prime Angus brisket, in his opinion. But the guy has cooked over 100 briskets each day for over a decade so I imagine it carries some weight.
In my preference for steaks, I like both. But it depends on the cut. For a Ribeye I'll take the grain fed. For a filet I'll take grass.