Here are two of my prospects:

Model 2003

Model 2004
My choice for the 5 series are more personal than technical. It's a great mid-sized executive sedan which means more space/legroom for me since I am over 6 feet. The styling, like the rims as I mentioned, are enough to swoon me hehe especially for the 2004 variant. Available in manual and RWD, it must be a joy to throw around some bends and I can live with its 6 cylinder engine.
I bet that the 3 series is also good but I guess I fell in love with the 530i
because it's the only one I got to ride in more frequently (belongs to an uncle of mine) and I haven't been lucky enough to ride in any 3 series.