Re which I like the best : today..
Well the E39 is the go to Daily and Hammer it in the hills, the E38 is the weekend cruiser and the E61 does everything and gets you there quickest.
Sum it up, and pretty much in my order of favourites....
E38 - Cheapest, quietest and the one we are taking on a 2000km SI trip, sit back relax and smash the distance out.
E39 - Daily sporty lots of fun, noisier then the E38 for trips though
E61 - Sporty and bigger, not as much character as the E39, Technological tour de force compared to the other two