I would say April if it were me. We're from Texas, so we are plenty accustomed to the heat and humidity, but that also means that we get plenty of them and like to escape it for vacation.
I would much rather deal with the crowds being a bit higher but better weather, because it just becomes miserable when it is too hot, at least in my opinion. DW is a teacher and since she won't take time off for vacation during the school year that pretty much limits us to Spring Break (March for us in Texas), Summer (no way), Thanksgiving break in November, and Christmas break in December. We have been over Spring Break multiple times, the week of Thanksgiving just last year, and just before and just after Christmas, to include over New Year.
Having been during Spring Break and Christmas before covid, and before the park capacity reductions, I can tell you that while the parks are busy they don't feel as busy to us. We've been in MK when it hit capacity and people couldn't get in, so now, to go at the same time, even if it is at capacity it's just not as bad.
Maybe it's all perspective, but I just don't get the complaints that it's somehow unbearable or impossible to do anything. It's Disney, it is always going to be busy, so if that's the case I would much rather go when it is less likely to rain (it's Florida, it can always happen) and less hot. We are on vacation, we put a certain value on our comfort. Good luck whatever you decide.