Midweek is usually best especially in any period of time in between special events/promotions/celebrations. Early this year we went from Superbowl Sunday to the Thursday after. Sunday was also the last day of the Lunar New Year celebration. Sunday was definitely crowded but Mon-Wed was amazingly low crowds. The flip side of that is that the operating hours are trimmed down with the parks sometimes closing as early as 8pm or 9pm after opening at 10am. Also, no fireworks or F! to end your night. With a 10am opening everyone can wake up & get to rope drop meaning that there is no quiet early hours to walk onto rides.
For me personally, I’d rather show up to the parks early for an 8am opening, even if it will be a busier day & have that quiet early hours to walk on rides, then once it starts getting crowded (and/or too hot) take a midday break, coming back refreshed to tour until the park closes at 11pm or midnight.