D/s is reactionary, so I don't have a favourite kink / fetish. It depends on the person, the context, my mood and so on. Here's a non-exhaustive list:

• Bondage (especially rope bondage, shibari) particularly creative applications, like predicaments; gags, restraint in general
• Sensory deprivation and prolonged bondage
• Any form of power exchange, including tasks, restrictions, and rules etc
• Humiliation and degradation (specific to the person)
• Sensory deprivation
• CNC (given the appropriate degree of trust)
• Anal / all manner of insertables
• Service submission

I am a sadist and a variety of things involving pain. Again, this depends on the person - not all pain reactions are enjoyable pain reactions. This includes, but is by no means limited to:

• All forms of impact play (caning, flogging, paddling, etc)
• Wax and temperature play
• All manner of clamps, pegs, ziplines etc.
• Emotional sadism in all its diverse forms