This is probably going to be a love it or leave it topic.
I tried using apple juice, wine, water and some weird combinations and finally gave up on the whole idea. My opinion is
it is just another expense that doesn't add much value to the finished product so I quit doing it and haven't looked back. I know some guys swear by it but I found I like my finshed product better when smoked "dry". I also found it made a mess in my smoker and even grew mold. My smoker is electric so that may be part of the problem but I also found that it took more energy (heat) to vaporize the liquid and when the liquid was gone the temperature would rise past my set point. In addition, I don't like the puddles of liquid that accumulate on the product especially fish.