simmons is younger and on a longer deal thus he helps wizards contend now and fits the timeline of their younger players. This move ensures that wizards trade beal without going into a rebuild and still remain a 7-8 seed while improving their team in the longterm.
Whereas beal is a few years older but is a better fit and provides great spacing which the 76ers need . This move shall help 76ers contend for a championship in the near future