Huh. WotC adventures are not as good as 3pp? News to me. I own quite a lot of 3pp modules and mine them for ideas mostly. Run a few of them. Rats of Waterdeep by
@M.T. Black is a fantastic little module. I've run it for about four different groups now and I've loved it every time.
OTOH, I have Necromancer Games Necropolis and I couldn't even begin to slog through that. Sorry, but when your first boxed text of the adventure is six paragraphs (and meaty paragraphs at that) long, with an optional seventh. And cartography that looks like a 5 year old did it. I'm more than willing to stack anything WotC upside that.
I dunno. I've played Strahd, Dungeon of the Mad Mage, and Hoard of the Dragon Queen. I enjoyed two of those quite a lot, although, to be fair, Mad Mage left me cold. I've run Primeval Thule - and again, I'll stack any of the WotC modules against those - Ghosts of Saltmarsh (an okay adventure. Possibly better with a different group), Dragonheist - tons of fun. I really enjoyed that module. I've also run Candlekeep, which, again, is a fantastic module. Lots of stuff to hang on there. And some really cool adventures. Now starting Phandelver and so far enjoying it immensely.
So, I gotta say, I've had far more hits than misses with WotC adventures. I dunno. I like 'em. Maybe I just have really low standards.