I've been happy with 1Password for teams. They have a white paper, which outlines their encryption strategy clearly, and their family of apps have worked great.

I've been happy with 1Password for teams. They have a white paper, which outlines their encryption strategy clearly, and their family of apps have worked great. Of course, when sharing 'vaults' with team members you have to remember that each vault is only as strong as the weakest master password of everyone on the team.