We've really only just scratched the surface of Dartmoor but thus far my favourite place is Fingle Bridge and the Teign Gorge. I take my team there each September for a walk to get to know each other better.
You can park at the top at Castle Drogo and walk down and back up but I prefer starting at the pub at Fingle Bridge walking up the gorge, down and then back along the river. We stumbled across The Duck Race on Easter Monday at Fingle Bridge which is an experience!
There's something about the scale of the gorge and the running water that reminds me of my smallness in a way that is very refreshing.