I used to play M:tG, but a tragic run in with some area hoodlums lead to the loss of my collection.
I've also played a really fun/simple TCG called Magi-Nation. There was a cartoon, and gameboy game, for thisgame. After the base set though they started adding too much to the game and it fell apart. You can still find the cards on EBay. Few years ago I bought 6 boxes, 216 packs, of it for around $30.
If you're interested in a tactical based TCG, check out Pox Nora (
www.poxnora.com). This game plays like FF:Tactics and M:tG combined. There are free decks you can play with to get the hang of the game. You have to buy the runes to use in your deck if you want to upgrade them, or play for rank. There are eight factions that each have their own strengths and weaknesses. If you don't mind spending a lil loot on something you'll never physically hold, it a good game.
If free is your thing, check out Elements card game. It's online, free, and fun.