The Geneva Bible was used mostly by the Puritans. The Bishop's Bible was favored by Episcopalians.
The problem was the notes found in each Bible. They were good translations with only some differences in the translation.
The Hampton Court Conference was held to try to get a unified Bible for the Church of England.
Dr. John Reynolds, who attended the conference said, "that a translation be made of the whole Bible, as a consonant as can be to the original Hebrew and Greek; and this to be set out and printed, without any marginal notes, and only to be used in all churches of England."
He basically wanted the word of God without anyone's opinion or interpretation in it.
The KJV doesn't have any notes, and King James backed it.