Since I am strictly a fan of 20th century, specifically the mid to late 20th century (up to the present) classical music, most of my choices will be decidedly not exactly "smooth and sweet".
My favorite is probably, Elliott Carter’s, Cello Concerto (2000). Fred Shery on cello.
I also love Joan Tower’s, Music for Cello and Orchestra (1984). Lynn Harrell on cello.
And, György Ligeti’s, Cello Concerto (1964). Alexis Descharmes on cello.