Best 'Lead Generation' websites for software companies?

Using OptinMagic.io for few months now and getting some good result. Highly recommended.

Linkedin, Quora, PH, Crunchbase :)

You can use apollo.io chrome extension to get leads from any websites

For generating the lead ,you can use LinkedIn, Facebook, Quora, Reddit and other B2B sites. For managing the leads from different platform, you can use Corefactors AI CRM(https://www.corefactors.in/)