My rankings are below. I am not responsible for any hurt feelings or drunken arguments that may ensue.
8: Unova. They just suck design-wise and type-wise. It also had the 3rd Fire/Fighting starter, which just adds to the pile of general garbage.
7: Johto. Bland mono-types. Meganium has too many weaknesses, and three of those are gyms in Johto. Typhlosion is terrible when it comes to design and overall battling (in my experience, both using it and going against it). Feraligatr is decent but nothing to write home about.
6: Kalos. Let's just say there's a reason everyone picked Greninja and leave it at that.
5: Galar. Like Johto, they're bland mono-types. Although I will admit, their designs, despite being a tad cartoonish, are much better than the Johto starters.
4: Sinnoh. While many people really like the Sinnoh starters, each of them has at least one quality that leaves a bad taste in my mouth. They're good, but not that good.
3: Kanto. The Bulbasaur and Charmander lines are great, and I don't hate Squirtle. Kanto had some pretty good starters, although I feel Game Freak should try to completely forget about them until Gen 14 or so.
2: Hoenn. These were a really good set of starters, and I understand why people like them. (Mudkip FTW!) Good ideas behind each, lovable and memorable designs, and nice for game-completion. My only problem is that something about Treecko feels a bit lacking and not enough.
1: Alola. All three designs nailed it. Rowlet is adorable, Litten is adorable, and Popplio is adorable. Then when they evolve, their designs lead to interesting places. A ghostly archer, a tough wrestler, and a singing mermaid. Their exclusive Z-Moves are also pretty nice.