Since you don't want to lower your car on c/o, BMW PS springs and bumpstops, Koni Sport or Bilstein Sport dampers and a M3 front sway bar. Cost is similar to the PS kit with much better handling.
+1 to KW street comfort if you are considering a c/o.
2007 E90 335i, TiAg, 6AT, ZPP, ZSP, ZCW, 6FL, HD
Quaife lsd, ETS fmic, GIAC tune, Dinan intake/exhaust, KW/M3/Meyle susp, Apex Arc 8, Mich PSS