I would definitely go the route of adopting a pre-bonded fixed pair... both rabbits being fixed is extremely important, especially for a first-time rabbit owner!
Although, if I'm completely honest, I might discourage you from getting a rabbit for kids, that fact certainly depending on the kids. If they really want a rabbit and are willing to put the work in it might be okay, but rabbits are realistically better family pets. I certainly would be hesitant to recommend to kids under the age of ten...
I was that age when I first got a rabbit, after years of asking, and I had to fulfill a very specific checklist (read 3 rabbit books cover to cover, make a PowerPoint presentation on costs and care, build a suitable hutch under my dad's supervision, have the allowance saving set aside for the things my rabbit needed, and find an adult female rabbit with a good temperament that came from a place that would continue to answer any questions throughout the rabbit's life.)
Before making the leap, be sure that all parties are invested! Rabbits are very poor first-time pets that can end in a great deal of heartbreak. Best of luck!