Had to vote for Cary Bates, but then again, he was the writer when I first started reading The Flash (back in 1972), so that's probably part of it.
Gardner fox
Robert Kanigher
Cary Bates
Denis O'Neil
William Messner-Loebs
Mark Waid
Mark Millar/Grant Morrison
Geoff Johns
Francis Manapul/Brian Buccellato
Robert Vendetti
Josh Williamson
Other
See Results
Had to vote for Cary Bates, but then again, he was the writer when I first started reading The Flash (back in 1972), so that's probably part of it.
Mark Waid.
Runners-Up: Messner-Loebs, Johns, Bates. I think once it's had some years behind it, Williamson's run will also come to be well regarded.
Going by that rule of thumb, Frank Robbins should be my favourite. Since, I believe, the first issue of THE FLASH I ever got was THE FLASH 180 (June 1968) on account of it being one of three comics in one of those "Comicpac" bags--what my parents got for me when we were at the department store. That was the infamous "The Flying Samurai" which struck me as rather racist--I really didn't like the comic book and it put me off buying THE FLASH for a few more years. The next ish I picked up was 208 (August 1971), which had an Elongated Man back-up story (probably the reason I got it) and Robert Kanigher wrote the cover story; however, this was when the comics had extra reprints and that one had a John Broome Flash story, which sold me. It was all those reprints in the comics that got me into reading THE FLASH full time.
I'm gonna say Mark Waid, I thought his run was really good.
I went Other.
Specifically Mike Baron.
He revamped Wally West Post Crisis, and was the first to really write Wally as The Flash. His run only lasted 14 issues (and one annual) but a lot of his ideas helped shape the 1990 TV series are stil used today in the current CW series. He laid really solid groundwork for all the great writers that followed.
I believe I originally voted for Mark Waid, but I will say that Mark Millar and Grant Morrison's short work on the series are some of my favorite issues in the Wally West era. They are incredibly underrated.
AKA FlashFreak
Favorite Characters:
DC: The Flash (Jay & Wally), Starman- Jack Knight, Stargirl, & Shazam!.
MARVEL: Daredevil, Spider-Man (Peter Parker), & Doctor Strange.
Current Pulls: Not a thing!