So from what I've read hispanos do the most damage pound for pound then.
Indeed. Below is the damage ranking in lbs for the 20mm's in AH and some examples of aircraft they are in:
RAF: Hispano (Mk's II/V): 4.03 (Spits, Tiff, Mossi, etc, and USN's C-Hog too)
JPN: Type 99 Mk II: 3.85 (NiK2, A6M5)
GER: MG151/20: 3.55 (190's, most 109's)
Sov: B20/ShVAK: 3.47 (La's, Yak 9U)
JPN: Type 99 Mk I: 3.42 A6M2, G4M
JPN: Ho-5: 3.35 (Ki-45, Ki-61, Ki-67)
GER: MG-FF: 3.25 (109E-4)
For reference, the Wirblewind does 4.0
These damage values are accurate as of Nov of 2012.
For the heck of it, below are the .50 cal damage as well:
US/UK: .50 cal Browing: 1.17 (US fighters, Spit 14/16)
Soviet: 12.7mm UBS 1.15 (Yaks, I-16)
Japan: 12.7mm Ho-103 0.99 (Ki-84, Ki-61)
Italia: 12.7mm SAFAT 0.95 (C202, C205)
GER: 13mm MG 131 .92 (109G6/14/k4, 190A8/F8/D9, 410)
For reference, the .50 cal Browning from gv's does 1.25 lbs of damage.
Also, all of the .30 calibers in AH (.303 Brit, 8mm, 7.7mm, 7.62, etc), do between .28 and .31 lbs of damage. Too close to worry much about separating them out.
This info too was accurate as of Nov 2012.