LG Neo Power. Basically IME, if they don't have grippers, they have to be long enough to clear the adductor muscles in riding position. And the chamois in the Neo Powers is good for as long as you want it.
Most of my shorts with grippers still have enough grip to stay in place if I turn the grippers out. But a lot of them (like the Shebeest SSS) wind up being too short if I do that. If you plan to turn the grippers out, make sure you're buying shorts about an inch longer than you want them to wind up.