Death and the Maiden String Quartet No 14 is among the very best of Schubert's works. Among his chamber works, it's bettered only by the String Quintet. Another wonderful String Quartet is No 13, Rosamunde. So too is No 15. The best version of SQ 14 that I have is by Henshel Quartet, but I wouldn't like to say it is the definitive best. If you like these works, you should also try the Fantaisie for Violin and Piano duet D 934 as it's not that well known but is very nice. All in all, I prefer Schubert to Beethoven for chamber music. It was once the other way round.