DC Jack 2.1mm vs 2.5mm

[jdduffield]

I’ve seen 5.5 x 2.1 DC Jacks for sale.
I’ve also seen 5.5 x 2.5mm DC Jacks for sale.

I read that the 2.1mm is a “snug” fit whereas the 2.5mm is an “easy” fit. What is best? What is considered more professional?

 

[chris.knudson]

2.1mm is pretty standard for guitar pedals.