My favorite ribs for smoking are the St. Louis cut Spare Ribs. They are nice and meaty with a good amount of fat that will melt down within the ribs as they smoking, making for the perfect bite after 5-6 hours of low and slow smoking. I prefer them to baby back ribs, as they are more uniform and cook more evenly over the entire length of the rib.
For this particular cook, I am using the Rec Tec 700 Pellet Smoker, which is a premium pellet smoker that has a nice consistent temperature controller. I even liked the smoker enough to build a Custom Grill Table for it. Definitely use whatever smoker you currently have to experiment and achieve similar results.