Recommended conversion settings for ePub?

Brand new to XTEINK and my X4. Howdy, all! I just flashed my X4 to Cross Point, and I'm wondering about the ideal conversion settings for ePub that make the text and images crisp, but still fairly responsive.

I haven't played with conversion much, but so far, it's definitely plenty quick on the book loads and page turns, but maybe a tad grainy? Not terrible; I just know the screen can do better than what it's showing.

What have you found to be the sweet spot when converting an ePub? TIA!