Not cherry picking at all.
Walt and Jesse are the main characters of "BB".
Jimmy and Kim are the main characters of "BCS".
Nacho = Hank.
Chuck = ?
Howard Hamlin = ?
Aside from that, I'd put Mike and Gus right there....and both of them are on "BCS", but with more screen time/story.
After that on "BB" you have Skyler and Marie....neither were fan favorites, to put it mildly. Walt Jr. had so little to do it became a meme in later seasons.
Hell, Chuck's arc,, Nacho's arc,, and Howard's arc > damn near every character arc on "BB", besides Walt, Jesse, and Hank. Who are the main characters on the show.
Fred.
Breh, you just proved you were cherry-picking right now cause you admit that Kim is one of the main characters of BCS yet you compared her to Skyler and Marie on BB, not Jesse. And you said Nacho is Hank but in your initial comparison you listed Nacho for BCS and Walt Jr. for BB.
Chuck = Skyler. Both were basically there to emphasize their foil against the main character as a combative relationship they couldn't get out of and that constantly reminded them of their biggest failure in life. Howard = Walt Jr. as the earnest minor player in that foil.
If you want to argue that Chuck and Howard's arcs are superior to Skyler and Walt Jr., that's one thing. But that's not the comparison you made, you compared Kim and Nacho to Skyler and Walt Jr. and that's not how the series worked.
Walt + Jesse = Jimmy + Kim
Hank + Mike = Mike + Nacho
Skyler + Walt Jr. + Marie + Gomey = Chuck + Howard + Schweikart + Cliff
Gus = Lalo
Lydia = Gus
Gale = Werner
Ted = Kevin
Tuco + Hector + The Cousins = Tuco + Hector + The Cousins
Schwartzes = Kettlemans
Saul, Huell, Krazy-8, Jane, Badger, Skinny Pete, Todd, Jack = Huell, Stacey, Paige, and ???
It's true that they handle the cast differently in BCS than they did in BB. Breaking Bad was more deeply Walt's story, so in the end FAR more happened with him than happens with Saul, which is why Better Call Saul often feels like a slow burn. They have more happen with other characters in BCS at the expense of having far less happen with the main character. Also as a result of that, BCS has introduced fewer meaningful side characters because they need to keep developing that same core, so they can't throw in a Krazy-8, a Jane, a Todd with as much weight because they need the time to keep Howard and Gus going. Even Gus's character arc has suffered a bit to the other supporting roles in BCS, I can barely think of Gus doing anything significant other than brooding. BCS has the advantage of building off of characters that were already developed in BB, so we can appreciate who Gus is an what he's doing in BCS even if his actual character arc is kinda flat and uninspiring.