The best way for labeling all the hiking trails/routes you've covered in the past

Short answer: print a map out and use a pen / scribblemap.com


Long answer:
1. Google Maps -> My timeline
Pros: capture most of the places you visited in the past
         automatic
Cons: miss some places where the data entry was not complete
          can't highlight the routes you covered (some versions can)

2. scribblemap.com
Pros: allows manual drawing of routes
         allows snapping to roads (better drawing experience)
         allows drawing multiple routes on the same map
         connect to Google Map data
         could export maps to GPX file etc.
Cons: Cannot import GPX file

3. mapmyhike and runkeeper
Pros: allows you to export your workout routes as GPX file
         user friendly app
Cons: doesn't allow overlay / multiple routes on the same map