ePub to... ? Best format for Kindle PaperWhite

Hi,

I just switched from Kobo to Kindle. (I'll be receiving my PaperWhite in a few days.)

My Calibre library is all in ePub.

Which format should I convert me ebooks to : mobi, azw3, kfx ? :blink:

I knew about the mobi and azw3 format, but not kfx. Which is the best?

I've seen here a plugin kfx output. I installed the KFX Previewer 3. Tried it. Converted one ePub. It resulted in a file 3 times the size... Is it worth it?

I use to have a Kindle, but that was 4 years ago. I need to get back into it!

Thanks.