I’d say monk chaplain krivis
The reason is that it allows you to switch from autoattacking to spamming Energy Blast for bossing/CM/endgame content without losing damage.
you still basically spam one button every few seconds, but it’s the same button (Energy Blast) every 4 seconds.
Krivis also provides nice buffs that last around 30 seconds (Daino/Zalciai) and have to be pressed only once every 30/50 seconds.
Divine Stigma is more for bossing, but can be used to boost your basic attacks,too, just like God Finger Flick (10 seconds +50% damage from strike attacks like Double Punch basic attacks)
or to double the damage of Energy Blast (again, mainly for bossing).
All in all, the build needs very little skills (Iron Skin once every 30 minutes, Aspergillum/Last Rites once every 5 minutes, Melstis once every 90 seconds, Aukuras once every 60 seconds, Daino once every 50 seconds, Binatio once every 40 seconds, Zalciai/Paraclitus Time/Divine Stigma [all only needed against bosses] once every 30 seconds).
That’s basically 11 buttons in total (if you exclude Capella/Energy Blast/God Finger Flick, which have their specific use), with 3 of them only requiring to be pressed once every 5 -30 minutes.
2-3 of them are ± for bossing, so you’d play mainly with 4-6 button presses per minute + holding the attack button the whole time.