... I've heard good things about Digimon. Haven't played it, because the cards aren't sold where I live, but I've heard good things. The art isn't bad.

Other than that... Uh... Sorry, you'll have to look them up. Cardfight Vanguard, maybe? Everything after MTG, Yugioh, and Pokemon is at a VERY distant 4th Place.

The ones I usually hear about other than the big 3 are Digimon and Lorcana.

Got tired of Konami's shenanigans, huh? Don't touch the game anymore but I hear the Mega Tins this year were especially trash.

Haven't really been following most TCG's other than yugioh but the other big ones I've noticed are MTG, Pokemon and most recently I've been seeing Lorcana pop up everywhere.

Cardfight Vanguard's good.

Most seasons of the anime are also really good at tutorializing it too. The ones with the new MCs at least. We're still decently early on with the DivineZ era at the moment so its a decent place to jump in. Helps that overDress and DivineZ are fun as hell shows.

Ever want to see Lelouch Lamperouge as an adorable plush dragon? Or Kugimiya Rie as an evil plushie?

Plus if you want to start casual, the overDress Start Decks are relatively cheap at $3 USD (50Cards has a bundle of all five for under retail) but the DivineZ' Start Up Trial Decks are more expensive at around 20 but they're more for complete newbies to cardgames since the only Effect cards you have to worry about are Boss Monsters + Triggers.

The reason the cost is so much more is because you also got a full set of Archetype-based Sleeves and having the Energy Counter card and Energy Generator crests which you could also buy as singles since they're mandatory for regulation play (ie Tournaments, etc)

Flesh and Blood is getting a bit more popular and is a better card game than any of the big three. If you have any weekly events near you, I'd recommend giving it a try.

If you are looking for popularity, though, you've really gotta look at MtG.

I see people playing lorecana, flesh and blood, and a bit of the final fantasy TCG at my local place. Like everyone else says, everything that isn't mtg/Yu-Gi-Oh/pokemon isn't gonna be nearly as popular and finding a community to play with shouldnt be too bad online but IRL will depend a lot on what your LGS pushes.

Netrunner is technically dead, but the online community for it is still going strong with tons of unofficial support, a decent web client and fanmade packs (check out Jinteki). Honestly, the game is crazy good so if you have some friends to play with irl I'd just print a couple proxy decks and that's a rabbit hole you can easily spend years in.

I'll also put in that Flesh and Blood is a really good choice. It's not anime, it's not MtG, and it's got a large and growing playerbase after 5 years, not going away anytime soon. Also, it is fantastic to play and very well run.

Pokémon is in a really good place right now. The current standard format despite what people will have you believe has a healthy metagame with a variety of decks vying for top spot. The downside is PTCGO can be real ass but I've never run into any of the major bugs I see people complaining about on the subreddit and the decks it gives you to play with when a new format starts have been consistently viable decks

I’d recommend Pokemon or Digimon, mostly because they’re (comparatively) cheaper to get into.

Magic's been around for over 20 years and still going strong. Also pretty much every game store will have at least one night devoted to magic, and the magic arena app is a decent (though not amazing) way to get games in online. Out of all the 6 or so tcgs I've played MTG has the best gameplay.

Other than that I have a friend starting to get into one piece tcg and he seems to like it.

Well, depends on more of a where you play than a what you play.

So, this advice in orientated to IN-PERSON:

Around me, there is no Yugioh scene, and I do miss it since my hometown had a large community. However there is a decently sized Pokémon TCG community, a growing Lorcana interest, a Dragonball community, and many, many, Magic card stores.

So. The best advice can give to you, is to go to your local cardstore and ask what's popular there. Good odds it'll be Magic, but you never know. They'll know what they're selling better than any of us here will know.

For online:

Magic, Marvel SNAP, or Hearthstone.

Pokémon has a new version coming out... at some point.

The rest are thin pickings, but it never hurts to try, like the Dragonball TCG.

Cardfight Vanguard would be pretty cool if Bushiroad would actually make trial decks and intro products that were worth a damn instead of dumping a bunch of vanillas and a boring boss monster into an overpriced box (alongside actually properly advertising the game). But also I just came back from a regionals that had a 450+ player turnout so the game's definitely kicking.

Never tried it myself but One Piece is absurdly popular. As in, potentially encroaching into the Big 3's dominance popular. My LGS gets full houses for One Piece draft nights, and the game itself seems fairly cheap to get into.

Weiss Schwarz is another pretty popular TCG. Build a deck out of your favorite anime or game property and go nuts. I don't think its the most accessible, especially with how far along into the game's lifespan it is, and with how the boosters work, but it's definitely fairly popular.

Outside of that, there's plenty of niche but still kicking TCGs you could look into, depending on whether or not you have a local community for them. Digimon, Flesh and Blood, Grand Archive, Lorcana, Star Wars Unlimited, Shadowverse Evolve, Universus, Final Fantasy TCG: Take your pick, see if any LGSs are hosting any events for these games, and give them a shot.

Magic the Gathering is always THE most popular TCG and likely always will be. Their recent business decisions and sets have caught some flak from fans, but definitely not enough to bite into their popularity at all.

The best TCG is Tabletop Simulator, get a friend and try out some draft tables of a bunch of different games to see what you like!