I like too many orchestrations to have a few favorites, but I do like the work of these gentlemen:
Frank Saddler, Jerome Kern's choice until his death around 1922;
Otto Langey and Harold Sanford, Victor Herbert's men; Sanford replaced Langey when he left M. Witmark & Sons for G. Schirmer in 1912;
Robert Russell Bennett. nothing else to say;
Ted Royal, underrated;
Hans Spialek, known primarily for Rodgers & Hart, but he surprisingly shows up as a ghost writer on other shows;
Don Walker, really versatile, but his work on Carousel, She Loves Me, and Most Happy Fella re stunning;
Hershy Kay, truly brilliant, and his NYC Ballet scores are amazing;
Phil Lang, gave Jerry Herman lots of glitter and beautiful work on My Fair Lady and Camelot;
Sid Ramin, Robert Ginzler, Irwin Kostal, Ralph Burns, the best of the "new" guys of the 1950s and 60s;
Jonathan Tunick, always amazing;
Alex Lacamoire, he amazes me.