When I first started to learn to can I always wondered about why there were two different types of canning jars. There regular mouthed jars like these that have "shoulders" and a smaller diameter opening. There are also wide-mouth jars like these that have no shoulders and a larger opening.
Some sites will say regular is better for pour-able contents like tomato sauce but wide-mouth is better for chunky items like potatoes. I disagree. I see two main differences between the types of jars and this is why I prefer wide-mouth canning jars for everything.
#1 Wide Mouth Jars Stack
Stacking is simply essential in a small pantry. The wide-mouth jars stack safely on top of each other. The regular cans have the same size top and bottom so they don't nicely nest on top of one another. To me, this saves space and pushes me away from regular mouth jars.
The general wisdom is that you should not stack jars that have been canned. The bottom can could be un-sealed due to bacteria or heat etc. Then as the top car sit there, the bottom jar could the re-seal itself without you noticing. This is the same logic to store the jars without the rings.
However, you can stack jars in the fridge after they are open. You can stack un-sealed jars in cupboards; say if they are filled with candy or coffee beans.
#2 Wide Mouth Are Easier to Clean
I know it seems obvious, but wide-mouths jars have a wider opening. However this means I can fit my hand inside the pint jar to clean it. I can't fit my hand inside a regular pint. Of course, I have small hands so a demonstration wouldn't convince you.
However Tim has large man hands, so here is a strange picture of two pint jars on his hands. Clearly his hand fits in the wide-mouth jar and does not fit in the regular jar. Meaning, he can clean the wide-mouth jar much easier.
#3 Wide Mouth Fit in My Cup Holder
So this may seem a little counter-intuitive. My wide mouth jars are round and some of my regular mouth jars are a bit square. This actually makes it so my wide mouth jars fit better in my cup holders in my car than a regular jar.
This of course is only relevant if you use your jars for drinking, not just for canning. I use my wide-mouth jars for making protein shakes.
There you have it! These are my three reasons for preferring the wide-mouth canning jars over the regular mouth jars. I will continue to use my regular mouth jars as I don't want to waste them but as they break I will replace with only wide-mouth jars. As their lids are equally easy to find, I will can much happier with my wide-mouth jars.