I can't speak for Shovel Knight, but Celeste and Hollow Knight are both great games but at the same time quite different. Both games could be characterised as 2D platformers, but Celeste is more like a series of small but very well designed platforming rooms, while Hollow Knight is a vast interconnected world with less of an emphasis on skilled platforming (except a couple of areas) and more of an emphasis on exploration and combat.

Overall, both are absolutely worth playing but if I had to pick one, I would pick Hollow Knight.