@Flik:
From my opinion (not very popular here I have to say haha) the SD figures like the Mini Big Head Chara Heroes as well as the Bandai Figure Collection were the best back in the old days. Thanks to their small size and cheap price, they allow to collect many characters, including usually neglected side-kicks. WCF figures are too mainly focused on straw hats and popular characters.
I'm so pissed off about the discontinuation of these two lines, I could not imagine how awesome it would have been to get small figures of the Oden flashback, Big Mom commanders, and I'm not even talking about the current arc !!!
I feel we do kinda get Bandai Figure Collection stuff every now and again. I recall one with Luffy, Robin, Chopper, Doflamingo, Law and Sanji. But they were all over. IIRC Robin and Chopper were Wano. Sanji was WCI and the others were dressrosa.
The problem is that most sets dropped from having 8-10 characters to 6. And once you get past the SHs and the endless Law and Sabo variants there's a chance for one char. Which is gonna be the likes of Marco, Katakuri or Kid etc who are popular.