I would like to discuss this if anyone is up for it. Like many "Ricardians" I don't believe he killed the "Princes in the Tower" though I do accept that he COULD have.
There is valid evidence to suggest that Edward IV's marriage to Elizabeth Woodville was illegal and therefore their children, including the boys, were illegitimate, so could not inherit. Indeed recent evidence has come to light that Edward himself may have been illegitimate.
There were always rumours to that effect, since hre mother herself said he was, but evidence may now bear this out, in which case Richard was rightful king.
Certainly in the late 15thC any rival is a problem, but the evidence against Richard is circumstantial to say the leats, and downright dodgy at times.
When the main evidence comes from the people who overthrew him, and is put besides their descriptions of him as hunchbacked and born with teeth you have to, at the very least, take a second look.