First of all, let me explain that I am a player of Invincible Heroes. I have never played Miracle 1. In order to answer your question, I went to see the introduction of Miracle. The following are some personal opinions for consideration:

1: There are many maps. So far, Invincible 3 still has new maps compiled by players. This may mean that Invincible is better than Miracle in terms of troop balance, tactics, and map editing.

2: Picture: Personally, I think the 2D picture of h3 is almost perfect. So much so that many people cannot accept the fake 3D and real 3D images of h4 and h5. To this day, h3 is still the most popular work among invincible players (including myself)

3: Characters, game background. The background of the invincible military units may have more "connotation", as they are all characters in Western mythology. Maybe it's easier for people to understand, accept and remember. It seems that no one who plays the game has not been exposed to Western ghosts and gods

4: Personally, I think the gameplay of Invincible 3 is invincible. You can, as ls said, bring thousands of soldiers to fight against a few others. You can also bring a few soldiers + countless magic + skills to PK others' K soldiers

The above is my personal opinion. If anyone thinks miracles are good, please elaborate. That's good, I'll play too. (I don’t reject games like Invincible, but I don’t have time to play games now)