I played a part in making Ubuntu a standard in both my previous and current companies. Though I myself am a die-hard fan of Slackware, Ubuntu has a nice balance of stability, hardware support and user-friendliness for use in the enterprise.
Do note that this is for desktop/laptop use. For servers, I would recommend CentOS/RHEL because that's what they're generally geared towards.
You should be able to negotiate on support licenses if you have a large deployment. Best to talk to their sales teams.