When it comes to depth of field there really isn’t any one good answer. Everyone always asks what’s your favorite f stop and your f stop does change your depth of field. Well there really isn’t any one that’s better then another. Each one has it’s own uses you just have to figure out what each one is used for.
For a couple years now I’ve been working with fly fishing photography and one thing I mess around with a lot is the visual focus plain. In this particular field you can get away with a lot when it comes to sharpness because a lot of the photography is about action, color and emotion. Using a shallower depth field is often considered best because it helps to eliminate a lot of potential problems in the background. For the longest time I’ve used the 24-70 AF-S but recently I’ve been testing the 85 f/1.8. It’s a marvelously tack sharp lens but being that it’s a prime lens takes some getting used to. The real benefit is being able to go down to f/1.8. That shallow depth of field allows me to do a lot that I couldn’t before, including working with the three main points I brought up earlier. So is there a great answer to this area? Yes! Go practice and see what you like.