OMG where to start, there is a lot of them but I have one from each of fallout games, Fallout 3 have Star Paladin Cross, who is boring, uninteresting, stupid *****, from fallout New Vegas we have Craig Boone, he is insulting and boring prick and Fallout 4 have 3 of them that I just hate, Preston Garvey, Paladin Danse and a X6-88, now this is my opinion and nothing can change it. sry

Preston Garvey, Jericho, X6 all spring to mind.

Everybody hates Preston. But I think he's more boring than anything else. I mean, there's no denying he's poorly programmed, but his main issues have more to do with Bethesda's laziness not the character itself.

Other than that, Fallout 4 companions are rather good as a whole. There's plenty of variety and they're most nicely written. I think most people would be able to find at least one or two they like. Fallout NV companions on the other hand are pretty bad as a whole, though each one for different reason.

I like Veronica the most. She's the only one that actually has a pleasant personality. She's quirky and funny. So, of course, the devs decided to make her silent as hell. She's the less talkative of companions, so the only way to hear what she has to say is stop what you're doing and talk. Also, her Battle AI is infuriating. She charges at everything, even with ranged weapons. And her perk, which would actually be pretty useful, became useless when they devs decided to give the exact same function to ED-E.

Boone has an awesome perk and a great battle AI, but he's depressing as hell. His backstory is actually pretty interesting but he's a one note character. Besides "regretful jarhead" there's nothing there.

Arcade is the most simply boring character I've ever seen. In terms of personality, there just is none.

Cass is probably the worst, though. Her AI is just as bad as Veronica's, her perk is completely useless... I just don't understand what the devs were thinking when they said: "Hey, let's add an alcoholic, near-40-year-old lady who curses like a truck driver to the game as a companion. And let's make sure her companion perk is totally useless and doesn't even work as intended. That'll be fun."

Though that's only counting the humans, because no way in hell I'm traveling with a mutant abomination. So I guess those are the worse.

I don't really like any of the Fallout 3 companions outside of Charon, Fawkes, Butch and Dogmeat.
They all lack any depth, and the only one with some backstory, or chat functions. I wish we got some more options, like side quests, backstories or anything. Something to give us a chance to connect with them, get their perspective or something. The closest we get is the characters I mentioned, aside from Dogmeat, who all have some level of narrative to getting them as companions. Jericho we just pay, Star Paladin just follows us, and RL3 and Clover we just buy.