The values I use on the export dialogue are entirely dynamic, based off the model I'm meshing...

The meshing angle is used first to approximate the density. The divide larger than and avoid smaller than are then manipulated together to attempt to produce the "most uniform mesh"......

The values entered in the divide and avoid fields are based entirely on the size of the object being meshed.....

then Poly count goals are looked at. The mesh angle is adjusted then the divide and avoid values adjusted again, until uniform and poly count goals are acceptable....