Eclipse of Whirlwind, rise of Spitfire were not determined by quality as perceived during 1939. It was industrial logic.
Whirlwind protoype contract 11/2/37. (Westland's near-bankruptcy, 10/35 had been rescued by 9/36 order for 169 Lysanders; again: ) 7/38 Ministers encouraged mariner John Brown and sparks AEI to inject equity: Spitfire wing ribs were from Westland. Reward was order for 200 Whirlwinds, early-1939, 200 more later 1939: cannon-armed escorts for RAF Medium Bombers vaulting over the Maginot and Siegfried Lines, beyond Hurri/Spit range (UK did not fund a small conscript Expeditionary Force for France until 23/4/39, intended for 1941).
Lord Nuffield was underway late-1938 building Castle Bromwich Aircraft Factory for Battles, changed early-1939 to Whirlwind, to which Spitfire Mk.II was added, 4/39...or so Air Ministry thought: (Spitfire's) "future was assured (due to) stubbornness of 1 man (N, insisting) on producing (all of all) 1,000 (at CBAF, so Whirlwind was) squeezed out”’ A.M.memo, 11/7/39, in E.B.Morgan/E.Shacklady, Spitfire, Key, 1987, P51: any colour you like so long as it's black. Nuffield wanted mass/same-same for his auto-production process: Spit easier than Whirlwind.
Add in Merlin finding so many berths; add in RR Experimental resources being dissipated over too many Projects; add in RR diversion to Supervising Merlin shadow production in quantities unseen since 1917...add in orphan Peregrine...and Whirlwind production slipped down the priorities list. It wasn't technical complexity, nor was it MG vs. cannon, that caused priority to Hurricane/Spitfire: it was the evident need as 1939 became 1940 for kit, anykit, even dodgy US types, NOW!