Franck definitely.I play Beethoven D major and Grieg G major with my partner this year and both are quite attractive too, imo
The Beethoven D major is nice. Have you learned Franck? Second movement is tricky, and certain passages in 4th movement as well. Very beautiful though. I first played it with a 26-year-old when I was 15.... I don't know how good it was.
Yes, I have played it. I remember having insane fear performing that one, some passages seem unneccessarily difficult and unpianistic.
Franck is definitely at the top.But to switch it around a bit, listen to Richard Strauss' Violin Sonata. Insanely beautiful, comes very close to taking Franck's spot in my mind.
Prokofiev´s F minor!
I happen to love Brahms' violin sonatas, all three.