In my opinion, to be truly confident that your data will be forever exclusive to yourself and people you choose is to pay for the service, to keep it running in the long run.

Otherwise, how is the service going to survive? They have to monetize somehow down the road to pay the bills.

See if you agree with what the creator of Pinboard says: http://blog.pinboard.in/2011/12/don_t_be_a_free_user/

I personally run a site called Handpick that helps people curate links and inform in a considerate manner:

http://handpick.me

I have paying subscribers who help me keep the lights on and do not have pressure to monetize my users' data in any way.

The question is: do you care enough how your data is handled to pay for the service?