Well top of the pack is subjective, lol
End Game is where real damage matters and that is why many use Stone, Sky and Sea because you need certain amount of damage to meet a dps check and maybe improve your rotation.
Dodging is only part of the equation, if someones rotation is awful well..
Palace while yes does give you live targets, things usually die too fast for one to actually learn proper rotations. It does give players some sort of an idea though.

In no way am i knocking down Palace as myself i used to enjoy it with friends and we almost made it to floor 200 back when it was first introduced
but alas one of the dps killed us all and we never went back, haha

Thinking about it i think if Eureka gave you actual levelling exp it would be great learning ground as well
Again we both have our own opinions and views so i was not knocking you down