I would put this, except I don't pay attention to who is the best, but who I like the most. So I'm ranking these by my favorites. Also the top 3 are the only ones where I like all 3.
1: Hoenn- Only region where I near equally like each one and Mystery Dungeon Grovyle is that awesome
2: Unova- While I GREATLY prefer Samurott over the other 2, Emboar and Serperior are tied for 2nd
3: Sinnoh- Infernape curb stomps, and I like Torterra more than Empoleon, but I can live with all 3
4: Alola- Incineroar curb stomps more than Infernape, but I like Decidueye, neutral on Primarina though
5: Kanto- On one hand Charizard is my favorite Pokemon. On the other, Venasaur is my least favorite
6: Johto- I like Phlosion and Gatr, but aside from Venusaur I greatly prefer the Kanto trio
7: Kalos- Differed opinion on each. Chesnaught love, Greninja really neutral, Delphox only fire starter I dislike
The reason Kanto is behind Alola is because I just hate Venusaur that much and Incineroar is my 2nd favorite fire starter and 3rd favorite starter overall. I may be neutral towards Primarina, but I don't dislike her anymore. However what puts them ahead of Johto is that Charizard is my favorite Pokemon and Blastoise is probably my 3rd favorite water starter.