Bold midcard, Italics-Main event, and both is borerline
January: Nothing most of the month, started big feud with HHH at the end.
February: Top level feud with HHH
March: Kane
April: Edge
May: Edge
June: Hogan*
July: Undertaker**
August: Rey
September: Benoit
October: Benoit, Edge, Rey, Eddy, Chavo
November: Benoit, Edge, Rey, Eddy, Chavo
December: Brock.
*This wasn't exactly booked like a top feud.
**Angle was almost an afterthought in this ME.
I think you can count the SD six months and the build up to them as being major feuds. They got everyone over and was the second biggest feud on Smackdown.
They couldn't give Angle a top line fued with Lesnar when they were setting that up for WMXIX without making someone look weak.
Granted everything before July was crap, but the feud with Edge was done with good intentions (and had a memorable blow-off), and Hogan, Kane and Taker are fairly over and faces. A feud with Taker or Hogan, to the average mark, is better than a feud with Benoit or Edge.