For pure aesthetics and difficulty, it's MacKenzie for me. For challenge and playability, Ross. For creativity and uniqueness, George Thomas - even though his is a small sample size. For lasting imprint and design standards, C.B. Macdonald and then Seth Raynor following him (how many template holes and green complexes did he create?) For originality, fun and quirkiness, Old Tom.
Flynn's great in his own right, as are others I left off, i.e. Colt, Alison, Tilly, Park Jr., Langford/Moreau, Maxwell, Thompson, Travis, Watson, Braid etc. but those are my guys and if you made me pick one, it would be George Thomas. I marvel at everything he did in his short time span and only wish he would have done work outside the state of California, as he could have been a monster. Amazing he concocted taking an elevator to tee off a hole. How cool is that? LOL!