Magic the gathering might be better designed as a card game on paper, but the PC games based on it are atrocious.
I don't disagree.
The Duels of the Planeswalkers games are the best games, they look good and play good and have decent AI, but deck building is extremely limited in those games (and deck building is a huge part of Magic, so that has always felt awkward).
There is an old game which is an RPG based around deckbuilding, but it's ridiculously hard and everything is kind of awkwardly handled - you ante cards, start with ridiculously low life, and the enemies you face have low life as well. So you basically have to abuse the game's flaws in order to win; basically an exploit game. You basically can't play slower decks until very late in the game. The basic idea is good (have a basic deck, walk around to get more cards for your deck, defeat the evil bosses of each color) but the execution is horrible.
Then there's Magic Online, and that's just the card game in computer format. So this should work, right? No. The interface is abysmal, the graphics are horrible, and you have to pay for all the cards you use, which would be fine if not for the crappy engine. There's a sizable playerbase though, with online tournament results being very important in order to understand the paper metagame if you want to be a tournament player. If you don't mind the shoddy interface and crappy-looking graphics, it's as deep as the regular card game.
I've played all three computer game types, see.
I'd like to see a game with the RPG idea (start with a few cards; win cards when defeating opponents; enter dungeons and beat special monsters to gather especially powerful cards; race against time with evil masters of mana taking over the world) without its poor poor design fallacies (that enemies are the same difficulty throughout the game, being insurmountable at the beginning of the game and a cakewalk later, the low starting life for both you and your enemies, the harsh harsh punishment of losing your deck's best card when losing a match) with Duels of the Planeswalkers graphics. That'd definitely work.