Might as well post some of my own now...
Colonel Silver's resources - The decision to give Silver so many soldiers hinders a lot of aspects of the narrative. It not only makes his defeat against Goku ridiculously anti-climactic (at which point his additional forces have inexplicably disappeared, no less), but also makes a lot of the forces of superior officers seem underwhelming. White seemingly only had a couple of dozen jobber soldiers as did Blue, so Silver having what seems to be an entire legion is utterly absurd.
The Wedding Dress filler - Leaving aside the hole of how the dress survived the previous fire and Roshi's Kamehameha, the whole plot with the Octagon is quite possibly the biggest plot convenience in the series. Somehow, a couple of items from going to locations with characters who had no idea about the furnace leads to Chichi gaining all the items needed to block the furnace's hole like some dumb JRPG quest. It also doesn't help that this is what's used to end the original anime on and not the more climactic finale of the 23rd Tenkaichi Budokai.
Fake Namek - Just utterly pointless. Most of the filler that came before it at least provided experiences to have the characters grow as either fighters or people, such as Goku's 22nd TB training or Gohan's adventures in the wilderness. This provides nothing other than wasting time and is also completely out of place in terms of the build up portion of an arc, as it neither provides any threat compared to the battle with the Saiyans nor build up for the battles to come. At least some of the contradictive fights such as Mutaito > Goku or Pure Boo being the strongest Boo helped offer some kind of build up in their narrative, rather than being a vapid time waster.
Garlic Jr. Arc - I would've actually found this to be OK as far as filler goes in concept, with it offering the Z-Warriors to shine without Galu there for once. In execution though, it falls apart completely by trying to put a Movie villain into the anime's canon when his movie can't possibly occur in the main timeline. We can't assume things happened differently in this timeline either, since Movie 1 footage is reused for flashbacks. It also didn't help the way Garlic Jr. was defeated was the most anticlimactic in the entire series. All it took was to destroy a nearby planet that even Kuririn could've probably done if not for Gohan being the last one standing. Also, mind control's always a boring trope.
Inside Boo filler - The powerscaling inconsistencies are too apparent to even bother mentioning. Not just that, but the entire thing is just so boring, beyond some humour in Vegeta having a fear of tapeworms, there was nothing to keep it engaging. Even having Gohan, Gotenks and Piccolo be mind controlled would've been better than just illusions, since that'd at least offer some sense of tension when Goku and Vegeta are fighting them.
There's also numerous fights and smaller moments such as Mutaito VS Goku, Ginyu in Bulma's Body, Vegeta seeing SSJ Goku on Namek, Popo showing the pecking order to the kids or Pure Boo being the strongest Boo, but all those moments were pretty minor in terms of screentime, so they'd fall a tier below these picks imo.
or Mutaito > Galu.
though (other than Maron's body, I guess).
