My advice would be to get one that can accommodate at least a couple of racks of baby back ribs. Some here love smoking everything. I don't like to smoke chicken except for thighs which are amazing smoked with cherry or apple wood. I have tried to smoke turkey only to realize I much prefer traditionally prepared turkey. I don't think smoke enhances the flavor of beef - I prefer a charred steak or burger. But ribs and pork butt oh my oh my. Sorry hogs but you were born to have your ribs and shoulders slow smoked. I prefer ribs because they taste great and "only" take 4 hours or so. A butt/shoulder takes 1/2 day and even then you really are never sure when it will be ready to eat. So start cheap but make sure you can fit ribs in there...
Totally agree with your comments about ribs and pork butt. My favorite is to smoke baby back ribs. I have a large Weber grill that I use as a smoker. I put a small amount of coals on the back half of the grill along with wood chips and the ribs lay on the front. Just enough room for two slabs which is perfect. My ribs usually take 3 to 3 1/2 hours. If I am doing pork butt, I get up early in the morning and smoke it for 3 hours and then move it to the crock pot for the remainder of the day. Delicious.