Both are equally important for what they have to do.
In the herd, the buck is the most important because he is the one that will benefit the WHOLE HERD. Rather then a doe may just benefit a few litters. Because you can use the buck on everybody, he benefits many more litters then just the average doe. Depending on how many does you have, he could produce well over 100 litters per year. Whereas a doe will only produce 5 litters a year at most.
Your buck needs to be your best quality animal in your herd. When people look and comment on your herd, they first look and comment on the buck. He becomes the backbone to your herd. If you have a bad quality buck, you have a bad quality herd. Not always true, but it's very common.
I'm still such a new breeder that I don't have the best quality buck. Lance will suit me just fine for the meantime. I plan on buying another buck - maybe. If I produce an amazing buck, I'll just keep him. Cinnamon, a doe, is currently the best rabbit in my herd and I'm so proud of her. I doubt I'll ever sell her, just like her mother, Gracie. Maybe, when the two of them are done producing, they'll come inside to be house bunnies with my Elsie. Since I have such a limited space for my rabbitry, this also leaves more space for, guess what - more bunnies!
Of course when it comes to giving birth and being a good mother, that's where does have the title of BEST.