I lease a B7 S4 and am very happy with it. I opt'd for the S4 back in November '06 over the E46 M3, since I figured that as soon as my lease on the S4 is up the E92 M3 will be out. Unfortunately for you the E92 M3 will likely be making it state side in early '08, so if you could wait till then that is certainly what I would advise.
2009 E90 M3 | Silverstone II | Black Novillo | HRE P40's | Akrapovic Exhaust | Eibach Pro Kit | Jet Black Kidney Grilles | SSII Side Reflectors | SSII Side Gills | LUX H8 Angel Eyes | Macht Schnell Filter | Tecnocraft Envy Charge Pipe
"M3 drivers have no friends." - Jeremy Clarkson