For contacts, I actually don't worry about it much anymore... not like way before when it was either on phone or sim card storage and if you did it on phone, then often times it was a long task to move it from phone to sim to put on your phone OR the new phone you bought didn't have all the same fields available!....
I bought a Nokia contacts manager way back before Nokia PC Suite was a thing.
I look for exportability and importability and with windows, I cared about it less because technologies like exchange servers, ical are all available to public now. People hub I can just link multiple sources together... I do try to keep outlook as the main constant though.
In my early days with wm8.0 I struggled with google contacts being quite a mess actually because they tried to do you a favour or something and build you a contact list. I spent quite an effort cleaning up that list since it seemed everyone I had every communicated with was a contact
But now, I'm in favour of a People hub interface where 3rd party can hook in to bring their contacts over and you can just link them together. With the way things are going, it feels like there will always be something available to consolidate your contacts wherever you need them.