People rarely have a choice about end tanks. Generally space is an issue and dictates end tank design. All you want in an endtank is even pressure over the end of the core. This should be thought of in the negative direction. Dont visualize your endtank flow as pushing the air through the core, think of the core as a drain, and you need to distribute the air evenly to the drain.
The only time the endtank is a significant detriment is when flow velocity is high, and the cross sectional area is small between the tank and the core.
Flow distribution in the core is a function of shear stress in the endtank. Since the viscocity of air is extremely low, you need a pretty shitty endtank design before it becomes a serious detriment.
Basically you want some room for the air to move around, so that the velocity in the endtank is not excessive.
Velocity is the enemy of an intercooler, both in the core and in the endtank. This is a function of specific heat, which once again I will not bore you with.