Thanks BMW tuner

This is really a rough decision for me. Some people say I'm better off with the 4.4( which has the same engine as the 4.8 but the intake is different)
I even thought about getting the e70 chassis 4.8 2007-2013 x5 which I'm not to sure if that's a bold move or not but, basically don't want my x5 to be a money pit!! Any suggestions on which is the safest route besides the 3.0 which has good fuel economy but very limited on power.