Thought this question might make for some interesting discussion. Oddly enough, I'm not sure I have an answer to my own question but I'll muddle through.
I do rather relate to Erasthmedor - we're both nearsighted and basically kindly, doing harm only by accident or when deserved so I guess that would be my best choice. Oakenmir would be a good choice for me too. I like trees, a lot!
Also add which NPC you would LEAST like to be -
Sebastio - universally disliked, doesn't know when to shut up, so caught up in his own preoccupations that he cannot relate to the needs and priorities of others, really needs to get out more!