Well, right now John Moses Browning is the most inovated gun designer. Glock and Kalashmikov have nothing on him. While their designs are pretty good, Browning's have stood the test of time very well. If it wasn't for JMB's designs, GLOCK wouldn't exist, and Kalashmikov got a lot of his ideas for the AK-47 from the Germans.
Glock and Kalashmikov are also only famous for one design. Browning is known for several.
Kalashmikov-AK-47 (he designed other guns, but they are all pretty much based off the AK-47)
1919 Browning machine gun
M1918 Browning Automatic Rifle (BAR)
Browning M2 machine gun
Ithica Model 37
The list goes on.