I have tried several smokers and have made my own before. they all work fine, but some are less hassle than others. So I would ask how involved do you want this to be?
If you want set it and forget it then the top choices are bradley, little (or big) cheif, and cabelas has a nice one that i don't recall the name of.
if you want fairly easy and capable of doing low-and-slow BBQ plus some grilling then look at traeger smoker grills. I have one of these that i find very versitile and easy to use. load with pellets, set you food and temps and check now and then till done. I do smoked fish often, plus I do a lot of pork butts, ribs and even roast turkeys and smoked whole chickens. there are a little higher in cost but very versatile. the only thing I use my gas grill for now is steaks and brats. I also have a backwoods smoker, these are really nice for making BBQ and they smoke well. On mine I had to experiment a little to find how many charcoal briquettes to use to get the right temps, but it works great.
if you want old fashioned, stoke with wood smoker then you can build something as nice as you can buy. you can also buy a variety of metal smokers either wood, electric or propane if you do not mind monitoring the temps.
the biggest factor in my experience is to get something insulated so that you have less trouble maintaining the temperature you want. the smokers sold at
wal-mart will do a nice job but you have to monitor the temperature as they are very prone to the temps falling off depending on the wind and such. If you could make a little enclosure to put one into to keep the wind off it would probably work pretty well. My neighbor uses one of these and the only issue he has complained about is the wind changing the temps.
Cheers
Jerry