I've now watched every Digimon anime released to date and I... have opinions. First, let's rank them from best to worst in my opinion:
1 Digimon Tamers
2 Digimon Frontier
3 Digimon Adventure 02
4 Digimon Xros Wars
5 Digimon Adventure
6 Digimon Xros Wars - The Young Hunters Who Leapt Through Time
7 Digimon Universe Applimon
8 Digimon Data Squad
9 Digimon Adventure Tri
10 Digimon Adventure Last Evolution Kizuna
11 Digimon Adventure: (2020)
Unranked: Digimon Ghost Game (Incomplete currently)
Now for my opinions: Digimon as a franchise struggles to take hold due to lack of consistent vision, marketing, and merchandise. It feels like the rights holders don't know what to do with it, but they know people resonate with it. So far the current Digimon Card Game is the best thing they've ever made, and while quality has been increasing across the whole franchise for the last decade, it's still lacking consistency. Also it feels like there's a certain lack of media literacy within the Digimon community. I see people complaining about lack of lore in Young Hunters and Ghost Game all the time, yet they constantly fed it to us, even while being more episodic than overarching narratives. One of the biggest complaints I heard about Young Hunters is the end isn't built up to, and yes one part seems to come out of left field, but overall it was actually pretty well built up. Overall though, I have to say the franchise as a whole is legitimately entertaining and deserves a look at by everyone, but we even lack releases of most of the series in the US. There is no legal way to watch Savers/Data Squad for instance. The others are all on Hulu, Crunchyroll, and TubiTV, with an expensive DVD release of the first 4 seasons years ago and a modern blu-ray release of Digimon Adventure as well as the Tri Movies and Last Evolution Kizuna. In the end though, the biggest reason the franchise failed in the west wasn't lack of interest from fans, it was every video game until around 2013 being a completely different take on the franchise, no consistent universe, literally no merch other than for the main partner digimon until the Vital Bracelet line, and a failure to differentiate it from Pokemon, a series it's still accused of being a clone of. This is entirely on the rights owners and even DigimonCon 23 shows they still don't know how to push the product. But for now, it's over, in a few weeks Ghost Game ends and then all we'll have left is the Adventure 02 movie and the new webnovel which I can only hope isn't terrible.