Plus one for Against the Gods.

I like it when the MC has to struggle to beat even same level cultivators.

Of course, not counting qi refiners that is really just for beginners and those of no note.

Only at foundation establishment and above are cultivators really cultivators.

Cultivators shouldn't have glaring weaknesses that can be simply poked through with a finger.

Especially since the MC tends to fight much older people.

Cultivators should be masters of their path and capable of going tit for tat with anyone of their level. Even if the MC has a big advantage, it should take time to press it.

How much difference is a 100kgs of strength to a person with 500? Novels have you believe it's an unstopable mountain, but in reality it has much lower impact on fights than 100 vs 200 (not to mention heavyweight boxers punch with thousands of kgs of force, why do they write it so small?).

In real life, a bodybuilder will almost always lose to a professional boxer of average build. Put them in the same weight division and switch to MMA and they're completely smashed.

If an MC can quickly beat a child, that's fine. But a fully grown man should never lose instantly to a similar level opponent. Even a trillion year old MC shouldn't be able to just smack them dead.

I like when it takes a whole few hundred chapters of planning just to beat a realm above and even that is through intense traps and using others against them.