I haven't tried launchpad's git support so can't comment on that.
Most people I have worked with have used Github, it has organization support and groups within organizations can get specific rights to specific repositories e.g. "inkscape developers" could get commit rights to Inkscape repository. Jenkins integration with Github is high priority for CloudBees, so that is a good choice from that perspective. The downside pointed out by many is that Github is a closed source service but I have no opinion on that. The second viable option as I see it is Gitlab.com. It runs Gitlab enterprise which is closed source _but_ Gitlab Community Edition is also available for us to install ourself. I wouldn't recommend running our own Gitlab CE instance at this point in time due to limited time to manage it. For organization and group support in Gitlab I believe it works just fine but haven't tried it myself.