In my opinion, Sinnoh is easily one of, if not the best region. Platinum was just the perfect version, as it fixed the only complaints I've had about Diamond/Pearl: the lack of fire Pokemon and the slow pacing. The region itself was pretty unique with this certain mythological feeling it gave off. Also its design was well thought through. I loved how Mt. Coronet divided the region in two, with each part of the region having differences, like the forms of Shellos, for example. Additionally, I really loved most of its cities. Canalave, Snowpoint, Sunnyshore, just to name a few. The landscape was also pretty interesting, as it took place in a colder setting than usual and still included many interesting places, such as the swamp and the snow routes in the north (in my opinion these routes weren't even annoying, but I might be the only one, though, haha). The tropical post-game island was pretty awesome, as well, as it had many intersting locations that would not have fit the mainland of Sinnoh (volcano, dessert, etc.). And while I'm at interesting routes and towns, don't forget about that amazing music which was playing there. Sinnoh easily had the best soundtrack of the main series (Unova is at a close second, though). Only the story was a bit... weird? I did like it (as I think in general the other region's stories weren't better, which a few exceptions (Unova (BW 1!) and Alola)), because it fit the mythological feeling of Sinnoh pretty well, but in my opinion it was a bit too much, introducing legendaries which could destroy the whole world. To sum it up, if you just look at Platinum, Sinnoh is my favorite region. And leaving out D/P is what I usually do when I look at Sinnoh, not because they were bad, but just because Platinum was so superior to them, in my opinion, haha.
