Some filler was good due to being either more character focused or filling in gaps that made points seem rushed. For instance, training segments that were skipped over in favour of a timeskip which makes the manga devoid of on-screen effort from it's characters. If I were to list all the good filler, they'd be:
The filler with Colonel Violet - Helped make her an actual character rather than some background scenery.
Goku's training for the 22nd TB - Made his gains feel far more deserved as we saw him venture out and actually train rather than just having a timeskip.
Practically any of the filler in the 22nd TB - Made many of the fights far more engaging, as well as Tsuru Sennin's assassination attempt on Goku make his character seem far less one-dimensional as we saw how he genuinely cares for Taopaipai.
Goku and Yajirobe searching for the Choshinsui - Far better in terms of making the power up feel deserved, since in the manga it easily the worst asspull in part 1 DB (apart from maybe Cyborg Taopaipai).
The training for the 23rd TB - Same reason as the 22nd.
Gohan's training in the Saiyan Arc - In the manga, Gohan goes from a crybaby in one chapter to chasing a dinosaur in the next, making his character development feel rushed. The anime thankfully fixes this.
Goku's training in the spaceship - Helped give him his own experiences as a character, rather than treating his existence like a plot device.
Any DBS filler involving Kuririn - Toei have done a good job at handling and highlighting his character.