While I'm knocking Airflo, let me add that RIO OBS and Grand are both horrible too.
In my opinion, they are not horrible lines, just lines used by many anglers for the wrong purposes. The OBS wasn't designed to be a line for flats fishing, or for delicate presentations to trout. It is an integrated shooting head and is designed to function much like a standard 30' shooting head with a thin running line connected loop to loop. Too many anglers find that this line, and its similar lines from Aiflo (Sniper) and others, allow them to feel their ultra-fast rod load. Therefore, they fall in love with it as it beats practicing to develop a more aggressive casting stroke. For casting large flies a short distance or used for distance like a shooting head, it's a fine line. I wish when they converted that taper to the Pike/Musky line they had increased the diameter of the running line more than they did, however.
As for the Rio Grande and similar lines like the Airflo Exceed, once again it's a terrific line for certain applications. When fishing that trico hatch on the Missouri I mentioned in an earlier post, that type of line would be horrible to use. However, those hatches don't last all day, and some days they don't come off at all. Even on a good day with minimal wind, the trico hatch on the Missouri is usually over by 2:00. Now what? Well, moist guys revert to chasing balloons. I've never enjoyed that so I'm more likely to fish streamers. But even better than streamers are hoppers. Just because it's not hopper season yet, doesn't mean that the fish won't eat a well presented, relatively small, hopper pattern. For years, I followed Dave Whitlock's advice and used a bass bug taper to present hoppers. These days, fly line companies no longer make a bass bug taper, or do so only in heavier line weights. However, the Grande/Exceed is the perfect replacement. In fact, the Exceed is probably the best hopper line I've ever used. All these various tapers get designed for a reason. Guys who don't like a taper usually discover that they bought the wrong tapered line for the application(s) they intend. Frankly, not everyone can afford to have a line for each application and that's where a standard WF taper can be a decent compromise.