Not much love for the 30i here but that's what I would recommend and it's the one I've got! Reason being that awesome 6 cylinder sound track which just can't be beat, 6 cylinder smoothness (which almost never gets mentioned when comparing to a 4 pot) and almost the same pace as the 35i but with way better reliability and not to mention there are way fewer of these around since they were only produced between 2009 and 2011 and in that time most purchased the 23i so quite rare in comparison which may help values in the future. Also this is what a BMW should be a 6 cylinder naturally aspirated front engined rear drive. Last of a dying breed or maybe its already dead but that is mainly due to emissions and government regulations rather then it actually being a better driving experience.