It's funny, if I were to make my own list there would be almost no overlap. Mostly because I hate having to prep anything, to be sure, but some stuff just doesn't seem all that overpowering to me.
For example, in my experience, Dracul is nearly impossible to get piety with, and way too easy to piss off); he's an excellent 2nd deity for late conversion and bloodpool exploitation, but in most dungeons if my deity roster is, say, Binlor, Pactmaker, and Dracul, I'm not going to go "yay, Dracul!" I'm probably just going to restart.
I've never really understood the mystique about Whupaz. Yes, it's helpful. Is it worth prepping (since you're limited to 5 potions and there are many other potent potables to choose from) and keeping in your inventory for the entire dungeon? Eh. Take a look at your "total damage" stat after a successful run, especially in a vicious dungeon, and then consider that (outside of one particular dungeon) Whupaz likely amounts to less than 5% of it.
And that's all it does.Same thing with "the hack" - until you mentioned undead, I honestly had no idea what anyone meant by it. (After all, everyone knows the
real secret to beating Naga City is
fireball spam.) I'll go for it with an Assassin, since I'm probably cheesing that particular deity anyway, but for anyone else it's a tough sell - it costs a lot of piety from a god who is fairly stingy with piety at low levels, and then you basically have to convert out immediately lest that same deity utterly screw you over for using his own boon.
~
Anyway, enough whining, here are a couple other items for consideration:
Glowing Guardian. At level 1, the
instant you find a GG altar you can boost your max HP by 12 (+5 starting piety and +1 from a sparkle). With a couple of glyph conversions and/or the rest of his sparkles you can boost your max HP by another ~20. Gain a level and you can then go back to level 1 with +5 base damage and another +10-18 max HP (Humility stacks with all the various HP boosters). The only other deity who gives anywhere near that much power that easily is Taurog, and Taurog is way more of a dick than GG these days. Dracul and TT actually make you suffer for their rewards if you want them right away, but GG is willing to give you some of his nicest toys right up front, very few strings attached.
Assassin. Sure, stat-wise the Rogue and the Monk outperform everyone else, but the Assassin literally breaks the game with Swift Hands, which may as well be called "win button." It lets him completely neglect his damage stat without penalty, something no other class can even attempt. Moreover, the optimal strategy for this class involves not expending any resources on any monster other than the boss. I'll repeat that for emphasis: the Assassin doesn't have to expend
any resources on
any monster other than the boss. Some classes call level 9 Animated Armors and Illusions "too hard." Assassins call them "lunch."