WSM for the win!
The WSM is really easy to use and holds steady temp like a champ, and you have three sizes to choose from 14.5", 18.5", and 22.5". I have the 22.5" and it is awesome!
I'm a little late to this party but hey. As a recent low and slow smoking convert within the last year, I'll share my 2 pesos with you.
First Figure out your budget. I truly think the quality of the smoker is more important than the type, believe it or not. The reason is a really cheap smoker no matter the type will likely be difficult to operate and produce less that stellar results and could turn you off to smoking.
Having said that, you certainly don't have to spend a lot either. But if you have less than $200 to spend to get started, you may want to rethink this endeavor. One reason is you will need more than just a smoker to smoke. You must have a good dual probe thermometer (or 2 thermometers) to smoke meat; one for the smoker and one for the meat. I am not aware that any smoker, no matter the price and quality, have adequate thermometers on them. And you will need to be able to stick a thermometer in the meat and leave it to monitor the temps, especial in the early going to understand stalls and what not. Otherwise you will be constantly opening your smoker to check meat temp.
Having said all of that, you can get really inexpensive smokers that work and as someone mentioned you can make your own really cheap. Do some research and you will be surprised how easy it is.