What zerg units counter Archons after patch 1.3.3

If they are archon/zealot heavy, roach infestor will work just fine. Roaches are beefy units that can take a lot of hits from the protoss, and the infestors can use fungal to keep them out of range anyway. Alternately, you can neural the archons and use them to help you take out the zealots.

Pure roach is decent but not fantastic against it.

Mutas work well if they don't have too many archons, but as you mentioned you do need to magic box them (although that really doesn't take that much micro if you know how to use the technique)

Broodlords are great if you can get them out in time.

Brood Lords, or Infestors to NP the Archons both will do pretty well against Zealot/Archon. Fungal Growth will be good too- both of those units have relatively short range. Archons hurt but they're an awful lot of gas.

Ultralisk - has splash damage that works well against mass of zealots. Due to big size is also good versus archons.

Archons are slow. Exploit the immobility of the Archon with drops and counter-attacks.