From what I can see the Weber Smokey Mountain (also known as the WSM or Weber bullet) is the most recommended by far. There are a number of sites that praise them and I have not really found a single serious criticism.

There are similar, less expensive smokers but all indications are that spending the extra $$ for the Weber is money very well spent. The main advantage seems to be much better airflow control, which lets you keep temperatures stable for hours without having to keep twiddling the controls.

Here's a site dedicated to the WSM

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8