>>14265878No.
The forme change only happens AFTER the attack.
Ergo you have to attack twice to get the stat boosts from attack forme; once to switch (attacking with low atk), then again WITH the high atk.
In that context, you're saying that you'd rather hit second so the enemy hits you before your stance change... But remember that ALSO means you've got to get hit EVERY TURN in attack mode, while your defenses are down.
Whereas with a high speed, you have a better chance of sweeping with your preposterous attack and not even allowing Aegislash's weak defenses to get touched... And if you sense a risk of being outsped and KO'd, you just King's Shield, which has +(4, probably) priority, thus negating the damage, getting your defense back, and nerfing the opponent's attack.
Speed is good here, it prevents unnecessary switching once you enter the attack phase of your Aegislash play (after protect-boosting your Atk and probably speed, too).