>>28995143That's season 3. Tamers. Tamers is considered the must watch season. It was directed by Serial Experiment Lain's creator Chiaki J. Konaka and a really solid show all around.
>Adventure>Adventure 02>Tamers>Frontier>Savers>Xros Wars>Xros Wars The Young Hunters Leaping Through Time>Tri>>2899519802 is shit when you don't have nostalgia but it does have it's moments and some nice designs and fight scenes. It just falls apart in it's second half because they clearly didn't really know what they wanted to do. Really only worth watching if you want to see where the original kids go after Adventure. Probably will need some knowledge for if you want to watch Tri too. Like the new kids, and the new D3s. Though Tri is mostly glossing over them at the moment.
Avoid Xros's second show. Absolute trash. It was billed as a crossover season and then the crossover only happens in the last episode.
Frontier isn't really that bad but it's incredibly different and it's last third or so has an arc that is absolute garbage until it reaches the finale. If you like toku though I'd say to give it a watch.
Other than that they're all pretty good. With Adventure you have to wait until after the Devimon arc for it to really take off so I'll say give it some time. The show really finds a strong footing 14-15 episodes in. Same with Tri. First eight episodes are slow, the next set are great.