You should be well served ny a 18"-20" Mossberg 500 or 590, Rem 870, Ithaca 37. If you want to get smaller the 'pistol' like Mossberg Shockwave series 12 or 20 gauge or Rem 870 , or the Remington V3 Tac-13. Best to try the short ones before buying if you can as the recoil can be a bit stout. The Mossbergs are reportedly reliable with an accessory and the shorty Aguila rounds.
The Rem V3 Tac-13 seems to have a less snappy recoil.
