I think for me it's got to be wingspan

https://boardgamegeek.com/boardgame/266192/wingspan

Not the cards but the money is the Firefly (yes the TV show) board game was very detailed and beautiful.

Parks has very pretty cards (they are by different artists so vary a fair bit)

I picked up Faraway recently and like the art on those cards - slightly surreal fantasy theme.

It's not the most complex game, but Dixit has really beautiful cards, in my opinion.

My favourite cards artwork is also my favourite board game, Oceans ( https://www.northstargames.com/products/oceans ) ! Especially on the collector edition with holographic special cards, really cool artworks overall (and really good game too)

I really like Everdell’s card art. There are a lot more components than just cards, though: https://boardgamegeek.com/boardgame/199792/everdell

I'm sharing my current favorites here:

• Arkham Horror: Beautiful illustration, as well as a beautiful game in my opinion.
• MtG: Magic cards remain among the most polished and beautiful ever created, even if I hate the direction it has taken, and in general I appreciate competitive games less and less in favor of more collaborative ones; in fact my favorite way to play Magic is with the Archenemy format (there is also an excellent boxed product).
• Marvel Champions: I don't actually have this in my collection but it looks pretty cool, I have to admit I'm quite a fan of Fantasy Flight Games at the moment!

I really like the art style in Unearth. The cards are each different ruins to excavate.

“Secret Hitler” isn’t beautiful per se, but to me it has a wonderful visual style.

"Most beautiful" is really subjective, but I got Knarr for Christmas and the art is really nice.

Here's a photo of the components.

My favorite is meadow.

https://boardgamegeek.com/image/5949283/meadow

@SolarPunker One recent candidate to this is Abyss. The whole game looks great. #BoardGames

Innis may be a stretch for card based, but it's one of the most beautiful games there is.

Anything with Kyle Ferrin's name on it. Goddamn can that dude draw.

Not exclusively a card game but Brian Boru has beautiful cards.

Forest Shuffle is quite educational with its detailed cards and lovely art: https://boardgamegeek.com/boardgame/391163/forest-shuffle

probably not in the spirit of the post, but you can play tarot as a trick taking game with tarot cards.

or I guess any card game with a higher variance due to more cards per suit.

A new find for me, Sea Salt & Paper, has a beautiful set of cards depicting various sea creatures, boats, and shells as origami.

Really nice style, nicely done - and the box is very efficient!

I really like the Ascension art, especially the earliest sets

Call to Adventure, and it's not even close.

I don't know about most beautiful but Dale of Merchants and Ascension have some of my favorite card art. I also like Mottainai for it's aesthetic simplicity.