Hey Neil. Honestly, I'd say more from calisthenics in the upper body but more from kettlebells in the lower body. It all depends on the exercise, though - unilateral work (pistols, one-arm pushups, one-arm kettlebell military press, etc.) will not likely add much muscle because of the stability challenge, whereas exercises with less of a stability challenge (double KB front squats, weighted dips, weighted pullups, etc.) will generally add more muscle. Thanks for the question, and keep watching!