I also played in high school. Right when The Dark came out, or maybe revised not sure. But Revied was my main set that got me into it. It sure wasn't Fallen Empires. I quit around Ice Age, or maybe Homelands was what drove me to quit. I also really enjoyed the weird sets. I can't remember the names, but one was a bunch of samurai's with a eastern theme. I don't even think those sets are legal anymore.
I started playing online last year again, because i'm old and don't have time to hang out with a bunch of sweaty 16 year olds. I do miss my after school magic days though. When I played a bunch of people had all the really expensive cards. Full dual land sets, with black lotus, mana drain, recall, etc... I could never afford those cards then. I remember wanting to save my lunch money and get a black lotus for $120.00 bucks from my local comic shop where we all played. Sure wish I had done that now. And I swear I remember I had multiple copies of that Green misprint Hurricane that's worth a small fortune.
I do really enjoy the online. I started again during Return to Ravnica. And it was a good time to get back in. It was the most popular set ever. And I like how much more balanced the game is now. I still hate that cards cost usually at least $40.00 bucks each for any good card you need to be competitive, and you always want 4 of them. I like playing the online drafts. They're a lot of fun, especially when you learn the sets first and know when to pass a rare for a strong common. With practice you can make out almost every time if you play smart.
The most popular formats are of course standard.
Also pauper is popular and cheap. All commons are used. Commander is a lot of fun. And since I played forever ago I like Legacy, or whatever it's called.
Another popular format is tribal wars. Which is all just cards of the same race or type. Elves, goblins, vampires, knights, etc...
But for online the best and easiest format is standard. By FAR the most popular.
Check out THIS WEBSITE
http://www.mtgtop8.com/
There you can see all the top decks in tournaments and see what you will be up against. Because people just copy these decks like a bunch of turds cause they can't make a deck on their own.
If you sign up online dont use the Planeswalker cards they give you for free, and never buy those cards, they are not legal in real games. And never buy packs! Onlly buy tickets i the mtgo store and buy from bots. MTGO Traders and Hot Bot are the best and only bots you need.
You can add me if you want. Jeremy_Forrest
I would also like to add, now is the perfect time to get back in. Because Geist of Saint Taft is finally phased out. That card was fucking cheap and everyone used it.