Well, I was definitely exaggerating a little. Marvel does have weird and fun characters. Howard the Duck. The Symbiotes/Klyntar. Slapstick. Captain Universe, The Howling Commandos (who are VERY similar to the Creature Commandos). Beta Ray Bill. Nextwave Agents of HATE. Agents of Atlas. Spider-Ham. The Great Lakes Avengers/X-Men. The Superior Foes of Spider-Man. Incredible Hercules.
It's just that...Marvel's universe feels more consistent and grounded than DC's does, usually. DC feels like a patchwork pastiche of different genres and tones, while Marvel usually maintains a more consistent tone. And that's because DC actually IS made up of a bunch of different characters acquired from different companies, and who all interact with each other fairly regularly, if only due to the MANY Crisises. For a good chunk of time, DC wasn't afraid to be a little silly, and it made some the characters more memorable, at least in my opinion. DC was just willing to go that extra step crazier than Marvel, usually.
When a obscure DC hero shows up, I feel like they KNOW they're a little silly and play that up a little. When a obscure Marvel hero shows up, they're usually treated fairly seriously, and there's a attempt to make them cool. Marvel just doesn't have that tongue-in-cheek attitude with most of their characters. Everyone LOVES Detective Chimp, but everyone KNOWS it's a silly idea. But, if the 3D-Man shows up? There's a even chance he'll be taken seriously. The POWER is usually considered silly, but they still take the CHARACTER seriously, more often than not.
And Marvel characters have the tendency to brood more than DC heroes, on average. That kind of takes the fun out of it. It's less fun if a "lame" hero HATES themselves for being lame. DC characters tend to own their weirdness a little bit more. On average.
OR Marvel goes the opposite way and just turns them into a complete joke with NO personality, making them pretty one note. Like Captain Ultra. Swarm. Stilt-Man. Paste Pot Pete. NFL Superpro. Mind you, DC does the same thing.
And Marvel has VAST swaths of characters that kind of fall into the same broad categories.
There's the Mutants...who all basically have the same origin story, but somehow usually make you feel like you're missing something whenever one shows up you don't know about.
There's the Teen Heroes...who all basically copy off of Spider-Man's 60-year old homework.
There's the Copy Heroes...who are basically backups of the popular heroes. They'll even joke in-book about there being 10 Spider-People. And 3 Iron People. And half a dozen Thors. DC does the same thing...but usually those groups feel more like a "family" rather than a bunch of coworkers who have the same uniform. In DC, the Bat-family all hangs out in the Batcave, the Superman family all mostly know who Clark Kent is and sometimes visit the Kent Family Farm together, and the Flash Family all hangs out together outside of fighting crime. The Spider-People...don't have that as much because Peter Parker MUST keep his identity a secret.
There's the Alternate Future Heroes...who are all copies of their ancestors by design.
There's the second-tier Avengers...which has quite a few characters who just kind of exist in the background for fight scenes, most of the time. They don't really have interesting powers or stories, they just kind of stick around.
That doesn't make them BAD characters. I just think they don't stand out as much as some of DC's more obscure heroes. They just tend to blend together more than DC's heroes, at least to me. And DC is guilty of ALL of this, too, especially with Batman (just replace Mutants and Future heroes with Multiversal variants),
And a LOT of them really CAN come into their own under the right writer. Nova really became something special after Annihilation. Darkhawk's had a few attempts to make him REALLY interesting (Shame those books never seem to sell). It's just that a LOT of those mid-tier superheroes just...get ZERO attention. Like Gilgamesh. Or Doctor Druid. Could a good writer come along and make them UNFORGETTABLE? Sure! But, they haven't yet.
Marvel's weird...just doesn't FEEL as weird and exciting as DC's, to me anyway. Even after all this, I'm not sure if I've really put my finger on WHY, though.