Is there a single sound that changes the whole feel of a conlang to you?

For me it's the glottal stop [ʔ]. It just gives a completely different feel to the rhythm of the language for me, like a certain clipped or 'stop and start quality', while languages without it feel more 'flowy' to me. This isn't intended to be a judgement on [ʔ], I really like it as a sound but when sketching out the phonetics of a conlang there's definitely times where I feel it's absolutely required for the vibe I'm going for and times where I feel it would absolutely kill the vibe I'm going for, which is something I don't feel so strongly for most other sounds, except maybe schwa.

What about you? Are there any individual sounds that completely change up how a language feels to you?