The first case I ever used on my Galaxy Nexus back in the day was a Poetic, and they're still a brand I turn to today. Although this time around we're recommeding the new Poetic Revolution for its premium, rugged, and dust-resistant design.
The V20 isn't dust or water resistant, like the Galaxy Note 7 it's trying to compete with. However, buyers can get at least some of that in this case from Poetic. It's a premium hard plastic and soft TPU case with a built-in screen protector that covers the entire device. The result is enough that they claim it's somewhat water-resistant, but we wouln't take it swimming or submerge it just to be safe.
All said and done this is one of the more durable and rugged cases for the V20, all for under $12. It's a good choice for those who are rough on a phone.