EZ drummer works for me. Very easy to use out of the box, easy to modify drum tracks, and the drum recordings sound great. I'm only doing home studio recording, but I have found it to be top notch. I have the standard Pop/Rock kit and the Nashville kit. Superior Drummer doesn't seem to offer much on top of EZ drummer that would make a difference for me, your mileage may vary.
YMMv I went from EZ Drummer to Superior 2. I would recommend EZ Drummer if you don't want to play with the sound too much, its descent right out of the box. Superior lets you get in deep with mic's, bleeding, pitch, mix, velocity thresholds, etc, but it's not as "easy" from the get go. but if you like to tweak things, then its money well spent.
* BFD2 -- this is supposed to be killer. A friend of mine has it and has said it's extremely difficult to use -- well he can't even lay down a track in Pro Tools, which really wasn't that difficult to figure out without reading the manual, but watching him try is painful. I assume BFD2 isn't THAT difficult.
* Addictive Drums -- They have their "Adrenaline" out now which is a ton more beats in the standard pack. In addition they just came out with three new add ons: Jazz Brush, Jazz Stick, and Funk. The original was the Standard, and Retro pak. You can do editing in your MIDI editor. I did complain over their lack of love for the cowbell in their beat list. Just posted a picture of Chistopher on their forum. But you can make and save your custom beats as custom fills.
* EZ Drummer -- well it's the cheapest initially, but when you start doing add-ons it comes out about the same.
* Superior Drummer -- I'm not familiar but I'd guess it's the full EZ Drummer.
* Then there's Reason 4 with Re-Drum. In addition to the synths and stuff you get a way of creating your own drum tracks as well. A little more "granular" control than with the others but also a little more difficult to use. And there are those "electronic synth" drums available.
So there you have it. All of them will tell you theirs is the best. I'm using Addictive Drums. I'm wanting the Funk pak and Jazz Sticks. I think the program is killer. The basic program is only $100 more than the basic EZ Drummer.