I almost always upvote any comment that I cannot identify as 'spam' immediately. I want to encourage people to read my work and comment on it. That's the whole freaking point, after all.
In fact, I save my 100% upvotes for comments on my articles for exactly this reason.
Yes, agree with @goldgoatsnguns. Unusually upvote commenters to my posts and at 100% as well. Gives them a nice boost for taking the time to read and comment and not just upvote.