The only shortcoming of a question like this is that it's like being asked, which is your favorite child (or pet or song or Dallas Cowboy or ...)?
St. Louis spares are an easy choice because they're darn near bulletproof, can be smoked pretty quickly, and are a great bang for your buck. Beef plate ribs are part of your DNA if you're in Texas, and a single rib is a meal unto itself. Beef back ribs (and those delicious little Beef Chuck Riblets) are basically bovine crawfish ... a bit of work for a little meat, but a lot of flavor. Traditional beef short ribs are better braised than on the smoker, but when done right are sublime.
Lamb ribs, while harder to find, are a true treat and are an amazing change of pace ... that alone is reason I'm about to do an order from Porter Road. Country style pork ribs (which, let's be honest, aren't really ribs) are great for a quick and easy dinner and make a perfect choice for homemade tasso. I've even been treated to venison ribs once and, while exceptionally lean, were flavorful and memorable.
Your poll made me want to basically "check all that apply".