I removed all skills from KRF heroes and tested them on Snapvine Bridge Iron (because the first enemy is the durable Gorillon) to find out their normal attack rate. In case of melee heroes, I checked Gorillon's health bar in order not to be deceived by animations (Saitam!).
Here are the results (recorded at 60 fps).
(*: rounded decimals to the nearest tenth)
0.6 s: Mirage
1.0 s: Alric, Cronan, Captain Blackthorn, Sha'tra, Kutsao, Saitam
1.2 s: Karkinos
1.3 s: Grawl*
1.5 s: Bruxa, Nivus, Dante, Kahz
1.8 s: Bonehart, Ashbite, Dierdre*
Mirage attacks 3 times faster than the dragons.
Dante's ranged attack rate is the same as his melee.
Here are their basic damage stat (excluding all skills) divided by their attack rate:
Alric: 15-28
Mirage: 22-33 (27-38 on Steam)
Cronan: 15-23
Bruxa: 11-35
Blackthorne: 22-41
Nivus: 15-45
Dierdre: 6-18
Grawl: 18-28
Shatra: 22-34
Karkinos: 12-35
Kutsao: 24-36
Dante: 31-45
Kahz: 23-41
Saitam: 21-39
Ashbite: 19-28
Bonehart: 11-33
anyway, numbers are just numbers.