All just my personal opinion
Beethoven, String Quartet op.18/5 — comparing recordings with the following ensembles: Amadeus Quartet (1961), Artemis Quartet (2011), Emerson String Quartet (1996), Endellion String Quartet (2007), Guarneri String Quartet (1995), Hagen Quartett (2012), Melos Quartett (1983), Quartetto Italiano (1973), Quatuor Mosaïques (1994)
Beethoven: String Quartet op.18/4 — comparing recordings with the following ensembles: Amadeus Quartet (1961), Artemis Quartet (2008), Emerson String Quartet (1996), Endellion String Quartet (2006), Guarneri String Quartet (1995), Hagen Quartett (1999), Melos Quartett (1983), Quartetto Italiano (1975), Quatuor Mosaïques (2004)
Beethoven: String Quartet op.18/3 — comparing recordings with the following ensembles: Amadeus Quartet (1961), Artemis Quartet (2010), Emerson String Quartet (1996), Endellion String Quartet (2005), Guarneri String Quartet (1995), Hagen Quartett (2012), Melos Quartett (1983), Quartetto Italiano (1972), Quatuor Mosaïques (2005)
Beethoven: String Quartet op.18/2 — comparing recordings with the following ensembles: Amadeus Quartet (1961), Artemis Quartet (2002), Emerson String Quartet (1996), Endellion String Quartet (2008), Guarneri String Quartet (1995), Melos Quartett (1983), Quartetto Italiano (1975), Quatuor Mosaïques (2005)
Beethoven: String Quartet op.18/1 — comparing recordings with the following ensembles: Amadeus Quartet (1961), Artemis Quartet (2010), Emerson String Quartet (1996), Endellion String Quartet (2008), Guarneri String Quartet (1995), Hagen Quartett (2003), Melos Quartett (1983), Quartetto Italiano (1972), Quatuor Mosaïques (2004)
Totally addicted!! In most of baroque Europe, the number of chamber music works for deep string instruments is rather small. Also, viols were very popular in France and in England (to some degree), but rarely used in Italy in baroque times, but at the French Court there was an entire school of famous viola da gamba players…