What would you use as a sortable, globally unique, ID?

The objective is to have an ID that has the following two inherent properties:

• globally unique: if two different nodes generate an ID, the possibilities for them to conflict are practically zero (hence no autoincrementing IDs)

• sortable: the IDs, even those generated by two different nodes, can be sorted or partially sorted making it far easier to order events (hence no UUIDs)

What would you use?