You still decide which player or planeswalker the equipped creature attacks.

If, during your declare attackers step, the equipped creature is tapped, is affected by a spell or ability that says it can’t attack, or hasn’t been under your control continuously since the turn began (and doesn’t have haste), then it doesn’t attack. If there’s a cost associated with having a creature attack, you’re not forced to pay that cost, so it doesn’t have to attack in that case either.