I really hated the linking of google to phone to SIM to facebook, because if you ever have to reset your phone its a huge pain in the ass to do them all over again.
I also was coming from a windows phone that synced to Microsoft Outlook
(SIM cards are also obsolete I feel. They only hold basic information)
My solution was to just make everything into google contacts. How?
1. In outlook export all contacts to vCard format (which can be opened nicely in excel for further editing)
2. Export all contacts from SIM card to vCard format
2b. Export all phone contacts to vCard format (but you really should of been saving all new numbers as google contacts to start)
3. In Excel quickly glance over all the many fields (majority of which will be empty anyways) and edit as needed. Personally I only kept Names, Emails, Phone Numbers
4. In Gmail, Import various vCard files. They will be added to you My Contacts
5. There is a merge all duplicate options. You can double check the sited entries before going through with the merger. It's more or less 100% accurate in my opinion.
6. If there are any discrepancies like 2 different mobile numbers/or emails, both will be saved. You can go back and choose which to keep or keep both
Delete all outlook/sim/phone. you can make a master vCard from google contacts before hand for your paranoia
Voila all your contacts are now google.