Here is what I think.
The e38s are a good reliable car.
I'd look for a late model....2000/2001 740i with the Sport Package.
I'd only consider an e38 with the Sport Package because to me...they're more sporty. They have the same wheels as the e39 540i Sport Package...you can't miss them. They have the //M on the wheels and on the steering wheel. I like sporty and luxury. And they're fun to drive.
Like this one.
I love the e65/e66......BUT
If you are considering one of these used....DO NOT BUY the first year models...they have bugs and just give you software problems. Some of these first year 7ers have them....NOT ALL. Unfortunally some of these members have had to go through those troubles and you can read about them.
So I'd consider looking at the vehicle history report to see what all has happened. Perhaps a 2003/2004 if you can find one used.
The e65/66 are more luxurous than the e38s. They have more room and more comfort.
Like this one.
But if you want to go older than e38. The e32 750i/750iL had v12 egines.
The best thing you can do is...go drive them to find which one suits you the best.
It also depends on how much you're willing to pay.
Good luck!