That’s a horrible question! It’s subjective, of course. I guess you want to know what they play as well…
Here’s a selection.
Stefan Dohr, principal of the Berlin Philharmonic, plays amazingly and plays an Alexander 103.
Radovan Vlatkovic is one of the most meltingly musical soloists, and plays a Paxman 20M.
Katy Woolley, principal of the Concertgebouw, Amsterdam, is a phenomenal, creative horn player with an enormous, warm sound all over the range; she plays an unlacquered Alexander 103.
Alec Frank-Gemmill, former BBC New Generation Artist, has alternated between several different instruments including an Alexander 103, a Paxman and a Schmidt triple (he sounds lovely on all of them).
And Dennis Brain, soloist and Philharmonia principal (who died in a tragic car accident in 1957 but is possibly the most influential French Horn player of all time) ended up on an Alexander 90, a single Bb horn.