For me, I picked Artifact. At it's core, the gameplay design just beats the others for me, and the monetization model is by far the best of the bunch. 20$ for unlimited drafts is great, and you can pick up most constructed decks for much cheaper than any of its competitors (because dead game). It's pretty sad most people just aren't willing to give it a chance.
Unfortunately, Valve has just gone completely radio silent, and seems content to just let the game die. I'm guessing they're preparing for some sort of free to play overhaul or something, but the lack of communication, combined with no progression or ladder system makes the game pretty hard to actually recommend to people.
MTGA would come second. It's just a very solid adaptation of the physical game (with some very annoying issues with how it handles ceratin rules and interactions). Unfortunately, the parts where it deviates from the physical game are where it sucks. The focus on no-sideboard gameplay just ruins the meta, as there is no way to make an overall balanced deck without a sideboard. So you either make a deck that beats aggro but loses to control, or the other way around. The meta also kind of sucks, with way too much control decks running around. Control just isn't fun to play against, but this particular version of it doesn't even have a win condition, so you either just concede or you have to sit there until your deck runs out. I have no idea why the latest set decided the deck needed a buff.
The limited modes are also completely busted. Draft against the AI just doesn't work, and sealed is way too expensive. Plus, playing them is just shooting yourself in the foot, as you don't get wildcards from opening packs. The economy is also super shitty. The real money transactions are much too expensive (ad kind of scammy), and the free to play rewards are stingy and Wizards is slowly but consistently making them even worse.
Eternal is pretty much just MTG, but with not broken limited modes. The asynchronous drafting system actually works here, and the sealed mode is super well made and very affordable. But overall, it's hard to recommend when MTG exists, as I feel like it's still the better game at its core. The cards are just kind of too boring here.
PTCGO is way better then the complete lack of anyone ever caring about it would make you believe. Just a solid adaptation of the physical game with a monetization model that is still expensive, but no where near its competitors (except for Artifact).
Shadowverse is kind of bad. The gameplay is just too simplistic. It used to be super free to play friendly, but that's not even all that true anymore, as most decks are filled with expensive legendary cards.
Hearthstone is whatever. The gameplay is just too simple, and the monetization sucks.
Gwent is just too boring to me. Most matches are basically just you doing the same thing over and over again with no really significant ways to interact with your opponent, and the changes they make with updates just really don't make sense most of the time.
Faeria is cool and has a lot of interesting design decisions, but it's also super dead.
Lord of the Rings LCG is pretty interesting conceptually, and I'm hoping they can polish it up until launch. It's not as good as the physical version, but still decent in its own right. The monetization model seems like it could be pretty bad (turns out, LCGs are actually pretty expensive for the amount of content you get), and right now it has a severe lack of content.
