A few notable projects where the canonical repo is still on SourceForge instead of moving to Github:

- LAME mp3 : https://sourceforge.net/projects/lame/

- KeePass : https://sourceforge.net/projects/keepass/

(Some people keep asking the KeePass developer to move to Github but he doesn't want to because "I'm not going to maintain a version control system." : https://sourceforge.net/p/keepass/discussion/329221/thread/9...)

Any other notable examples besides those 2?