Really depends what you're fighting. I have 2 barspells sets, 1 for max number and the other which just equips 5/5.

For stuff like higher tier voidwatch you're not going to resist anything with barspells alone, you're casting it mainly for the MDB bonuses WHM can get. Best to just go 5/5 and try and get a 0 damage proc.

For lower level things and on the rare occasions you're aiming to resist (carols/gear etc.) then I'll use things like Cleric's Pantaloons+1 to try and get it as high as possible.