After first finishing Silksong, then going back to Hollow Knight, then going back to Silksong for the second playthrough, I can say this.

Given the choice of playing either game, I would pick Silksong. It has glaring flaws that HK doesn't (mainly pacing and "collect 10 boar asses" quests), but fuck man the combat is just so much fucking fun whereas Hollow Knight feels really limited in its moveset.