Perhaps neither..If adding moisture to the meat, is it spritz or mop?   If you do either or both, what is the liquid recipe?

I'm more of a neither one kind of fella.  I tried spritzing BB ribs with Sprite once and Cherry Dr. Pepper once with mediocre results.  My daughter doesn't like sauce on ribs is the only reason I tried.  I just cook her a pork chop now when I cook ribs.

Spritz whenever I use one

I used to use a mix of apple juice and worcestershire sauce to spritz ribs many years ago.  I don't think I have done that since I have a pellet grill.  Sometimes I would put some liquid smoke in there too.

I have done both in the past, but mostly spritz.  Recipe changes, but a go to is a mixture of apple juice, apple cider vinegar and low sodium chicken broth.

I spritz my ribs with an apple juice, Worcestershire, salt and sugar. Works well.

I also will use the same spritz for pork butts.

The little of BBQ history I know, the Mop & the Spritz come out of the dry heat produced either by a half a steer roasted over wood coals on a spit in Texas and needing to be "mopped" every so often, or a Hog cooked in a Pit in Carolina with Hardwood coals needing to have a vinegar spritz thrown on it too.  Both cooked with hardwood, but neither having the benefits of a 100% hardwood pellet that will have 8-12% moisture in it!

A reason why, even though I have tried both version in my past, I find no need for it today!

The little of BBQ history I know, the Mop & the Spritz come out of the dry heat produced either by a half a steer roasted over wood coals on a spit in Texas and needing to be "mopped" every so often, or a Hog cooked in a Pit in Carolina with Hardwood coals needing to have a vinegar spritz thrown on it too.  Both cooked with hardwood, but neither having the benefits of a 100% hardwood pellet that will have 8-12% moisture in it!

A reason why, even though I have tried both version in my past, I find no need for it today!

I agree fully with the dry heat causing a need to replace the moisture lost due to dryness..  I don't find a need to mop or spritz when cooking on my Memphis or Green Eggs...  Are you sure about the 8 - 12% moisture level? It seems a tad high. My premium hardwood pellets are listed as 5 - 7%.

I'll spritz pork butt or brisket with apple cider vinegar before I wrap depending on how they look, but otherwise neither.

Both.  For pork ribs I mix apple juice and blues hog Tennessee red and mop. Any other times, if I feel like it, I'll spritz.

Yep, those are the %...The heating pellets are usually less...

The little of BBQ history I know, the Mop & the Spritz come out of the dry heat produced either by a half a steer roasted over wood coals on a spit in Texas and needing to be "mopped" every so often, or a Hog cooked in a Pit in Carolina with Hardwood coals needing to have a vinegar spritz thrown on it too.  Both cooked with hardwood, but neither having the benefits of a 100% hardwood pellet that will have 8-12% moisture in it!

A reason why, even though I have tried both version in my past, I find no need for it today!

Daddy always called it sopping the meat.  He'd tie an old sock or something onto a mesquite branch and sop the meat.  Some vinegar, lemons or limes, vegetable oil, maybe a beer and what ever spices we could find.  It was always good or we were hungry.  Think hungry was the answer.

I spritz ribs with plain apple juice.

Neither - I cook without adding any moisture 95% of the time, the other 5% I use a water pan... my meat is pretty much always void of externally added wet ingredients.