Best: Suction Bombs or Splash Wall. Out of all the bombs, suction bomb is easily the best. You can literally throw it anywhere and it just stops people in it's tracks. Splash wall is also incredible on so many maps that have narrow chokepoints (ex: Urchin/Port). However the wall still works outside of chokepointed areas, and you can just throw it out if you're losing a fight.
Pretty good: Point Sensor/Burst BombsI personally think Point sensor is extremely underrated. You can practically spam point sensor, as it only costs 1/3? (not sure exact measurement) of your ink tank. You never have to worry about someone hiding in enemy ink, as you can just throw out a point sensor. It literally makes it impossible for someone to jump at you from a corner. Plus, even if you don't get the kill, if your team has a sniper it's super easy for them to pick it off. Even if no one on your team kills said person, they still constantly know where he/she is for 20? seconds. Burst bombs: E-liter. Do I need to say more? . Edit: Forgot Sprinkler, which is kinda self explanatory.
Map dependent: Squid beacons. Some maps (ex: Saltspray Rig) makes beacons so incredible that I wish Nintendo nerfed it significantly. On the other hand some maps like Port Mackeral has no good beacon placements.
Worst: Splat bombs. Splat bombs are simply outclassed by Suction bombs, Burst Bombs, and Ink mines. Burst bombs are amazing for close quarters combat, and you can even pick off people who try to run away. Ink mines can occasionally guarantee a trade in close quarters fight, and kill off unsuspecting people down a narrow hallway. Splat bombs can bounce off walls, which is nice, but it can also work against you. Somewhere like BlackBelly has railings that deflect the bomb in an unfavorable way.