I'm running the eibach "i" springs on my bilsteins. They're great. More daily-driver friendly than the H&Rs, and the rear wheels won't look dumped.
There are a number of xi drivers running the eibachs, all with good reports. Runs some searches.
Just don't upgrade springs (any brand) without doing the struts. You'll be supremely disappointed with the performance once the luster of the better stance wears off.
http://www.e90post.com/forums/showthread.php?t=664385