Some just want to build a serviceable drum track quickly and then move on to the fun stuff, whether that's playing your guitar or singing or programming synthesizers. Although I fall into that category, I realize that not everyone does. Bottom line is I'd say SD3 is for people who are really serious about their sequenced drums, who take their time tweaking sounds, and want no limitations. It has gobs of effects, many of which I've never used. It has a great drum-replacement feature that I've used only a handful of times. It has its own sequencer, but I've never used it. I do not run it from an SSD, and it can take quite awhile to load. As noted above, SD3 is HUGE, by far the biggest sample library I have.

SD3 has lots of expansions but they are more expensive than BFD's. SD3 is more configurable than anything else out there, which may or may not be a good thing depending on your style of usage (if you want to get up and running and sounding good fast with minimal effort, check out Steven Slate Drums). However, I don't automatically recommend it to everyone. I am a longtime Superior Drummer user, going all the way back to Drumkit from Hell, its distant ancestor. Not a BFD user here, but after watching others use it, BFD seems a little quicker and less fussy to set up and tweak to a good sound.

Bfd3 vs superior drummer