What size Mason jars are best / most useful?

[vex]

Hello,
Novice here. I'm still buying supplies and getting ready for my first fermentation and run. I don't have any Mason jars and was looking on Amazon.

What is the most useful size(s)? I suppose I need medium sized ones to make cuts with and maybe smaller ones to put final product in.

I assume most give jars to friends and family? What size do you give?

Any suggestions on what to buy is appreciated.