An Olds L-12 is still a good flugelhorn; I own one as well as its yellow-brass belled twin, the Reynolds FU-52. I wouldn't call it the best, though, although it's certainly more than adequate for just about any use. Incidentally, Art Farmer played a number of different flugelhorns over the years (Couesnon, Besson, Kanstul, possibly more); you can read a bit about one of his horns which is currently owned by Dmitri Matheny:
http://dmitrimatheny.com/fr_flugelhorn.cfm

I believe it was sold recently, but during a visit with Flip Oakes a couple of years ago, I had the pleasure of seeing the first Kanstul ZKF-1525 made, which was presented to Art Farmer. After Farmer's death, Flip (who designed horns for Kanstul) acquired it from the Farmer estate.