I use a propane smoker and really like it for what I do. It depends on how much you plan on using it and what you plan on using it for. Search some of the older posts, and if you still have questions feel free toask.
If you'll take a look at my "WWW" link below my posts, you'll see that I use a couple of charcoal smokers as well as a propane one. The large, black, square, upright smoker is the LP one. Quite a bit of the food in the photos came from it. It's a Great Outdoors Smoky Mountain gas smoker. They also make it in a charcoal version. As mentioned it loses heat when the door is opened but it will recover in about 5 minutes. That's why you only open it once an hour. Mopping/basting is very important for brisket.