Sensation-seeking / sensation-avoidant
Neophilic / neophobic
Emotion-seeking / -avoidant
...These aren't the classic ways we talk about personality. But why not? They seem to represent so much of the variety in people.
We have words like "bold/meek" but they seem mostly to connote bravery, dominance, etc. Even "thrill-seeker" seems to me slightly missing the point.