Just my opinions, keep in mind, I'm still a steemit noob.

• What types of contributions do you consider adding value?

I feel that what adds the most value is original content; articles, images, video. Vibrant discussions of those topics.

Too long (unless your target audience is expecting) and people tune out.
Too short (unless you are making memes) and there's not enough meat for discussion.

• What types of things will you upvote/reward?

Ideally - I would upvote those articles that catch my attention, make a good argument, or otherwise bring a perspective that I may not have considered. I've upvoted posts even where I disagreed with the content, but where the argument was well presented.

In reality - I browse through the topics that I know are going to be the ones to attract the most attention, trying to maximize curation rewards. I even find myself upvoting posts where I don't understand the language because the stats are positive for potential reward. And I hate myself for it.

• What types of things will you downvote?

I'm not really interested in down voting, unless it's something that is openly plagiarized from a known source and there is no attempt to represent it as a copy.

• What types of projects will you consider delegating SP?

I need to build up enough SP first before I should start thinking about how to use it.