I'd recommend upgrading your defenses because they will wipe out the troops that are attacking your base faster.. NOTE: When your defenses are being upgraded they can not attack.
If you upgrade traps it can not activate and it will be shown on the defense where the attacker knows it's there. So yes if you upgrade the traps it will wipe out armies but if you upgrade it it won't be easy. So just know your traps won't activate so I recommend if you do upgrade traps or defenses you should do it within the shield time so you won't be powerless when one of your traps or defenses won't work and gives the enemy an advantage.