Adric is just the Connor of Doctor Who, but I like both characters. I think the worst from the classic show are Turlough and Ben, they aren't my cup of tea.
Adric is nowhere near as bad as Connor.
I mean it's all just taste, but even then there are objective reasons why some characters are bad I feel. You need to strike the balance of not being an opinion police, which I admit yes, I have had a VERY bad habit of being, and pointing out when there are certain decisions that can harm something objectively. A character who ages it perhaps by representing a bad stereotype, one whose story arc drags it into a hole it struggles to get out of, one who is perhaps shilled a bit too much etc represent more objective problems. You can still like those characters for other reasons like the actors performance or other parts that are good, but I feel when doing an objective review need to at least acknowledge some of those faults, or not shut down anyone who does at least and try and understand why they would dislike it.
Doctor Who fandom is weird in this respect. Buffy fandom I can get on with as they do tend to point point more objective flaws.
Connor for instance regardless of whether you like the actors performance or parts of his story arc, I think it has to be said objectively he was problematic and fans aren't just picking on him because. He was involved in a creepy love triangle that nobody wanted to see. (One where if you think about it, he and Cordelia were r****d as she was trapped in her body with no consent by Jasmine, and he had been misled into who he was shagging. It turned out to be his daughter!) Connor also constantly undermined other characters relationships like Wesley/Angel who had to have a falling out for a year, before it just went back to normal, Cordelia/Angel who if you liked that yeah you were screwed (and even if you didn't like them together like me, seeing Cordy boink Connor was pretty creepy too,) he took time away in an already overcrowded cast, constantly went off the rails and attacked the other characters and had a ridiculously inconsistent power level. (One week he is made out to be a little bitch Faith can take down like a naughty kid, the next he can beat up Angel, who thrashed Faith, when Angels backed up by Gunn and Wesley,) and finally he tended to hit the same beats all the time. (This is obviously talking about S4 Connor, not the adorable, lovable S5 version.)
DW fans however, not only do they gloss over the bad bits, and shout down any criticism with personal abuse on some forums, they pick on the most harmless, inoffensive things like Adric and that 60th celebration Doom to absolutely shit on for all eternity.
Adric doesn't do anything as disruptive story wise as Connor. He is just a bit wooden and that's that! He doesn't get involved in a creepy love triangle with Nyssa and the Doctor, constantly attack the Doctor, tell the Doctor he hates him every week etc. To be honest Adric is more comparable to Oz, in terms of being just a kind of "he was there" companion. Seth Green is a better actor, but even then he arguably gets less to do so it evens out.
Again a character who does do shit like Connor is Donna. Objectively she doesn't work story wise, as she is made out to be better than the Doctor thereby undermines the main protagonist, insults him all the time and he takes it, is made out to be the best person in the multiverse, undermines the Daleks and Davros by thrashing them easily and Sarah Jane and Martha who have to be made into doofuses or genocidal maniacs so she can swoop in, she is openly misandristic etc. Yet she gets praised and Adric hated on?
I've often said DW fans remind me of Bernard from Black Books. For those of you who haven't seen it, Bernard is a hilarious character who seems to get angry at the most unimportant things but shrugs off things that would piss people off. Like in one episode his hapless friend Manny locks him out in the freezing rain through his own stupidity for an entire night and in the morning when Bernard shows up and Manny tries to apologise, Bernard just says "forget it." In another however when Manny tries to say "Let's paaaaaaaartttyyyyyy" Bernard threatens him with violence and says "don't you dare use the word party as a verb in this shop!"
That's DW fans all over. "What you've undone decades of Master/Doctor rivalry to make the Master into River Song. 4.0? Moffat has thrown out every single aspect of the Masters character and done it because he openly despises the character? Fantastic. Moffat truly gets the Master and has honored Roger Delgado. What's this a minor companion who was there for a year and had quite a cool ending, but didn't really do much one way or the other and whose actor was a bit inexperience? STAB, STAB, STAB, STAB, KILL, KILL, KILL DIEEEEEE!"
"What's this a bit of spin off material like Doom is a bit silly and aimed at kids? UNFORGIVABLE! Oh RTD wasted the 60th anniversary to do a circle jerk about his own era, and nothing else, and fills it full of cringe inducing right on nonsense and basically gets rid of the Doctor, whilst having him be demeaned for a man? Fantastic this man is our lord and savior."
It gets so frustrating.