Personally I like mounting them further back closer to the rear sight.
I do this for weight distribution though, not for any perceived advantage.
The further back it is the more head movement you can have while still being able to see the dot. The further forward, the less movement you will be able to accomodate before the dot is no longer visible but the easier you can see "around" the sight.
If you are planning on using a magnifier, you pretty much have to keep it up close to the front of the receiver to give clearance.
I am no longer participating in gun forums.