Health is scaled by level, attack is percentage based and mana is static- I cant see a way around it.
Attack is a %-based multiplier on your base attack, which scales by level. If anything its power grows more substantial on higher-level characters. It's totally analagous to the scaling health bonus, and the only significant discrepency are Orcs or the Trisword, which allow you to raise your multiplier.
Mana doesn't scale by levels, but the spells you cast it with do. BURNDAYRAZ and HALPMEH explicitly are based of your character level. PISORF is based off of base attack, which is pretty much a multiple of your character level. CYDSTEPP, GETINDARE, ENDISWAL, and WEYTWUT are used to get an extra attack against enemies; the effectiveness of your attacks increases as you gain levels. BYSSEPS scales with your base damage, which is based on your level. Both LEMMISI and APHEELSIK are used to leverage health regeneration, which is based on character level.
So I'd argue that both attack bonus and mana naturally scale with levels, even if it's not as explicit as the health boost.
I guess just I enjoy a less min-max style of play, where starting items aren't extreme and provide flavour, rather than advantage.
Then play purist human fighter. That's your tabula rasa. Otherwise, the whole idea of preparations is to improve your overall character standing. That doesn't mean crippling specialization, but it does mean focusing on the most cost-effective way to increase your strength.
I think more double edged preps would be ideal, something i think is reflected in the positive response to the double edged god perks.
To be honest, the only one I use is Binlor and Mystera. Taurog's penalty is also fine and my main beef is with the deity. Otherwise, I always go with +1 altar. Most of these need substantial help and are largely useless in their current state. In principle I think these are great, but the execution was a flop on most of them.
Wouldn't touch Tikki Tooki with a 10 foot pole. Earthmother is a consolation prize in the first place and not worth prepping. Glowing Guardian is extraordinarily painful unless you're going for hoarder, Jehora Jeheyu similarly unless you're going for miser. Taurog is a really situational deity to begin with. You need to find a way to boost your HP to use Dracul effectively, so taking a HP penalty is a deal-breaker.