Auto-translated
I believe that in Heroes 5, the creatures are much more impressive (considering the time difference between the games), but comparing certain things is pointless. It's like asking: what's better, a car or an airplane?
In general, Heroes 3 is the best, as it was the one that started the era of Heroes games, and Heroes 5 is essentially the same as Heroes 3, but in a more modern version (I didn't mean to offend anyone with this).