Strong recommendation - Image2Icon

[ghost]

I highly recommend Image2Icon (macOS app).

For Favicon, it will export the following:

Desktop Browers
16x16, 32x32 - Multisize ico
32x32 - Old Chrome versions
Mobile
57x57 - Non-Retina iOS, and Andriod 2.1+
72x72 - Secound generation iPad
114x114 - iPhone retina iOS ≤ 6
120x120 - iPhone retina iOS ≥ 7
144x144 - iPad retina iOS ≤ 6, IE10 Metro
152x152 - iPad retina iOS ≥ 7
180x180 - iPhone 6+
192x192 - Chrome for Android

You can also export for the following:

Folder
macOS Icon
iOS Icon
Android Icon
Favicon
Iconset

I don't work for them or anything. It's just what I use for icon anything. Everything I mentioned in this post is totally free, and you buy the full version it has a ton of other features.

Website & Appstore