I'm reasonably capable of finding things that interest me, that provoke thought. I'm not capable of forming opinions and observations outside my own experience. So I share things that make me think because I want to know what other people think. I share things I disagree with because I want to see if others agree with me or if I haven't fully considered them. I share things I want to know more about in hopes that somebody else will add more to the conversation. And I share things that I specifically know others will like, because in sharing those things I enrich the environment we have in common and encourage them to do the same as a result.

"What kind of things should I post" is an entirely appropriate thing to share. It asks a question. It encourages conversation.

To answer your question specifically from my viewpoint, I don't follow tumblr, the only people I follow on twitter are al-shabab and Rupert Murdoch, and I haven't logged into G+ in weeks. I want to see anything that someone else found thought-provoking - even if my reaction is to shout it down (I usually vote for things that actually required me to formulate a response, unless that response is a long-winded elaboration of "this article is stupid").

Memes and cat pics do not interest me in the slightest.

But that's just me. You may find a devoted audience who loves the cat pics you share. If cat pics are your passion, share them. You are likely to find others who share that passion with you. Clearly there's a market for Philip J Fry image macros, I just don't happen to be a part of it. Don't worry about what's important to me, worry about what's important to you.