We run multiple cookers...
We like to do chicken hot, dry & fast. Skin-side down on the racks most of the time.
For ribs, we have a new BWS Competitor (permanent, fixed water pan).
I think the moisture helps. Lots of folks disagree. Of course there's a LOT of other factors.
It ain't necessary to have a water pan. But, for ribs, I like it.
As someone mentioned already, it helps control the temps. So, consider the insulated/non-insulated factor. An insulated smoker can be hard to cool back down if you get it too hot.
Water helps to keep you in a sane temp range.
Might sound like an argument against an insulated smoker, but, how much do you wanna spend on fuel? What's your average daily ambient temp where you live?
So, the questions/factors can go on and on and on...
How THICK do you like the bark on your ribs?
I just like a thin caramelized layer...
I don't want the same bark on ribs that I do on butts...
The factors involved are "numerous", to say the least.
Anyhow, I like water --- as far as ribs are concerned.
However, be advised that many of my esteemed brethren maintain otherwise.
Full disclosure: I flunked kindergarten.
Only once. But, I flunked it.