The Spitfire VIII is truly the best overall in-game.
There's not too much too complain about with it, though compared to a IX the VIII actually maneuvers worse ... marginally. Those who fly Spitfires religiously know that well. Just dont forget a DT.
I personally like the Spitfire V the best. challenging yet still fun. It really shuts up the HOiccane drivers. as WW once put it, its only, if not, main disadvantage is its speed. I'd welcome a Spitfire Vc with the standard 1942 Merlin boost of +16 lbs. .. like in AH:I.
The XVI in real life had some 1000' difference concerning the 2nd stage supercharger kick-in/kick-out vs. the LF IX or the LF VIII (which we have in-game) but I don't know much about the AH:II Spixteen since i don't fly it much except on field-cratering runs.
Even if they do manage to fix the odd stall on the Hellcat, the Corsair's still going to be able to outrun and out-accelerate the Hellcat

through energy fights will be more interesting.