Yeah, Frog Princes are a significant upgrade for the NPCs over the Crazy Cannoneers they replaced. They hit about 40% harder while also having 20% more health. But that's because Cannoneers are absolutely terrible units. Fortunately province #20 has a 5-enemy encounter in it that includes frogs so I'm able to put up some comparisons between the three 'long range' units:
Squad size 3573
893x Frog Prince: 51,615~69,833 damage, 223,250 health
893x Faineant Frog II: 44,650~66,082 damage, 205,390 health
596x Rad Mortar: 42,316~70,328 damage, 178,800 health
596x Crazy Cannoneer: 29,800~49,468 damage, 190,720 health
It's apparent that Frogs are the best of the three stat-wise, but it's more important to note just how bad Cannoneers are. Even if they hit for max damage, they're still always going to be weaker than a Frog Prince. Even 2* Frogs are arguably better, though that one's a bit more up in the air because they lack a debuff. I included Mortars just to show how much better the Human unit is than the NPC one. Anyone who hates Mortars or says they're bad units, take a look at Cannoneers and see just how easy we have it whenever we have to face off against them.