Again, technically every KH title to date is part of the main story as each element relates to the two main PS2 but still, for conventional numbering the "Main" ones to this date still are the first game, KH2 and the incoming KH3. I realize I've badly worded my thoughts in my first reply, so my apologies for that.

I'm not dissing that all those spin-offs are not relevant as part of the main story at all from my part! I just think that, to be Sora's story, I can't consider any of the other KH titles as 'Main Games' in the canonical term when either the main characters in said sub-titles' individual stories aren't Sora, while sprouting many connections to the PS2 KH games. To me is like having a story about an apple tree and then for the next few chapters the focus is put on seeds from different trees with way different origins and features, with some nudge-winks near the end of those chapters to the original apple tree.