They have different aims. SuperCollider gives you outstanding timbral control, but patterning at the melodic or chord level is awkward. TidalCycles is a language for musical patterns, not for generating waveforms directly. If you want to mess with both, I'd recommend starting from the definitions of the synths in SuperDirt, the collection of SuperCollider synths that TidalCycles uses.
TidalCycles does offer a lot of ways to control the timbre -- there are a bunch of effects, including some magical granular stuff. And merely triggering samples at sufficiently high frequencies, particularly frequencies that vary over time, can generate some cool sounds. But SC will give you much more control over that kind of thing.