More than personality, the fundamental problem is that you don't conquer China from Sichuan. The Qing were systematically building an effective state in the beifang; luck and competence aren't an especially effective counter to that, not coming from a small patch of the nanfang. And obviously that's before Zhang Xianzhong's....quirks....enter the mix.
A guy like him could more plausibly succeed in the context the Qing had already stepped into: a declining Ming state, gripped by systemic issues and plagued by an almost incomprehensible number of simultaneous peasant revolts. In a situation of flux, a lucky warlord's following could potentially snowball much better. And if it snowballs enough....
From that perspective, what's needed is a sustained failure of the Qing system to create adequate leadership, from the moment it plunged into China proper, or even before then. A half dozen bad personalities and some worse luck might have stalled the Qing expansion after its first phase. That might be sufficient to prevent their success from distracting from their brutality and foreignness, as it did in our TL.
I don't know enough of the personalities of the early Qing to suggest specifics, but in broad strokes they were very competent. It would take a lot of mess at the top to disrupt the system once it had momentum.