Most firepower or most guns? In game or in real life?
In game I'd go with the 110G, with the Typhoon a close second. The 110 isn't much of a "fighter" though.
For a rough calculation, you can figure that 1 Hispano is worth about 4 .50s, with the rest of the 20mm being roughly 2.5 .50s, except for MG-FF, which are about 1.5.
30mm is tough, the range is negligible but the damage is awesome. I rate them about the same as a Hispano.
So in terms of .50s you have the following -
110G - 4 x MG151/20 (2.5 apiece), 2 x 30mm Mk108 (4 apiece) ~ 18 .50s
Typhoon - 4 x Hispano 20mm (4 apiece) ~ 16 .50s
Other planes with "heavy" firepower -
190A8 - 2 x 30mm Mk108, 2 x MG151, 2 x 13mm (.75 apiece) ~ 14.5 .50s
190A8 - 4 x 20mm, 2 x 13mm ~ 13 .50s
N1K2 - 4 x 20mm Type99 ~ 10 .50s
Spitfires with .50s = 2 x Hispano , 2 x .50 ~ 10 .50s
Spitfires without .50s are close... I'd say roughly 9 .50s.
Fighter with craptacular firepower -
Hurricane I / Spit I - 8 x .303 ~ 2 .50s
P-40B - 2 x .50, 4 x .30 ~ 3 .50s
C202 - 2 x 13mm, 2 x 7.92 ~ 2 .50s... on a good day.
109E - 2 x 20mm MG/FF, 2 x 7.92 ~ 3 .50s.
109F/G-2 - 2 x 7.92, 1 x MG151 ~ 3 .50s.
109G-6 - 2 x 13mm, 1 x MG151 ~ 4 .50s.
Yak-9U - 2x 13mm , 1 x 20mm ShVAK ~ 4 .50s
Note that on the 190A8 and 110G you will practically never be hitting with the 20mm and the 30mm at the same time. Granted, if the 30mm hits you wouldn't need the 20mm in the first place, but it shows them as having heavier firepower than they will ever bring to bear.
