CFS-3 might be worth looking at also, both for its "out of box" jets (late WWII designs) and its
Korean War mod package . The DogPatch Crew's cockpits for their F-86 and MiG-15 are among the best 'freeware' pits available for CFS-3.
In CFS-3 you can set up Instant Action dogfight scenarios very easily; you can choose any plane vs. any other plane that's loaded in your library, regardless of their default nationality when used by the game's campaigns. New planes are usually easy to download and install from sites like Netwings or avhistory.org. As far as I know, though, you'll be limited to early jet warfare -- in other words, no guided missiles.
CFS-3 isn't my favorite dogfighter but its expandibility and its SFX visuals make it worth considering. The "FirePower" commercial addon by Shockwave adds a few more Luftwaffe late war and 'drawing board' fighter designs.
My other recommedation is "IL-2: Forgotten Battles" with the "Ace Expansion Pack" installed over it (these can be purchased together as the "Gold Pack"). Jet warfare is limited to YP-80 'Shooting Star' prototype vs. German Me-262 and He-162 (and Me-163 and Go-229 as well as the Russian BI-1 rocket plane). On the other hand the default Quick Mission Builder is easy to use and you can set up dogfights of up to 16 vs. 16 with up to four different aircraft types on each side. The AI is fairly good and the damage model is detailed. There are plenty of piston fighters to choose from and the 3D cockpits are generally very nice ... the IL-2 series is the true successor to "WWII Fighters" in my opinion.