Why, you ask? Well, it's simple.
The director is voice actor and Rainbow Overlord himself, David Wald. He's directed the dubs for Vanitas no Carte, LOVE STAGE!!, Bloom Into You, Kase-san and Morning Glories, The Stranger by the Shore, and more. Do I even have to explain why these dubs are splendid? Given was no less, in the right hands.
The casting was spectacular. In my opinion, there aren't really any glaring differences in the main cast's voices. Plus, the English VAs add their own sort of flair to the characters, making it more enjoyable to watch.
Almost all of the team (including the cast!) is queer. If you don't believe me, take it from the director himself: David's tweet.
Lastly, what seals the deal: the fact that this show means so much to literally all of the cast & crew. For many of the VAs and crew members, it's been a dream for them to be apart of an all queer team, and also to be in a show like Given, that's already such a beautiful and important anime. Yung-I Chang (Haruki Nakayama) said in his video, "Please know that every one of us was hungry for this show, ever since it first came out in Japan. We really put our everything into this production, and I hope you love it as much as we do."
This is all to say, please, please, please, watch the Given dub. As someone who's been a fan for years now, this dub means so much to me, as it's created by people who cherish the show just as much as all of us fans do. They love it for what it is, a heartwarming queer story.