I'm relatively paranoid about data security (I run my own mail server, web server, cloud services, groupware, etc). I currently have an iPhone and am on the verge of buying a Samsung Galaxy S4 in the next couple of days.

To be honest, the only thing that gives me pause is that the more I read about Android, the more data I hear about going to Google. Most of it I don't care about, but I do care about the privacy of my contact information, and to a lesser extent, my calendar data. As a Software Engineer that's worked in Big Data as well as credit card transaction processing, I know what companies like Google can (and do) do by correlating that data with other data, so this isn't an unfounded fear. I also feel that it's not my place to give other people's contact information to Google. I'm trying to become more comfortable with the concept, but I'm definitely not there yet.

Are there reasonable precautions I can take? I know I can turn off syncing with GMail before I add any contacts, and that will help. Is there anything else I can do?

Are there apps that I should seek replacements for and avoid?

Are there other settings I should look for?