I love Magic. A lot. It pleases me greatly to see a thread for it.
I haven't played MtG:O, so I can't comment on that; I'm slowly building my physical card collection; and I'm a huge fan of Duels of the Planeswalkers despite its shortcomings.
If you want the cheapest path to playing, it's gonna be DotP. If you want to see to it that you and your friends can stay on relatively equal footing regardless of gaming budget, then I would again say DotP. But if you want the full experience, then DotP really isn't for you; at least, it's better suited as a quick-and-ready way to play Magic on a whim or when your friends aren't available to play with.
I haven't actually played MtG:O, but from what I understand of it, I recommend the real deal over it. If for no other reason than the fact that getting the cards you want on the cheap is pretty easy. Don't know what you want exactly? Check in with
Channel Fireball where you can buy 500 packs of randomly selected commons from your expansion of choice for $6 a pack (note that these packs don't come with land cards, so you'll have to buy a land package, too). That'll get you started with a ton of deck options. There are a lot of strong, useful cards available among commons, by the way. You can buy singles from them at good prices, too. So once you play a bit and get a feel for what kinds of cards you like most, what style of decks you want to play, you can find the best card options by reading up on
MTG Salvation's wiki and forums.
I'm a bit biased toward the real deal card game. I'm very much a "I want physical media" kind of guy. However, the ability to play the real game on a decent level without spending big bucks is nice. Winning big tournaments with a box of commons may not be terribly likely, but good times with friends is definitely doable. And, should you want to upgrade to a more high-profile tournament ready deck, it's easy to get a good foundation on the cheap and can get uncommon and rare singles without dropping a fortune for the most part.
Just stay away from that
Jace, the Mind Sculptor mythic rare if you are wanting to protect your wallet. lol
Side note: Admittedly, I'm a sucker for intro pack/theme decks sold at the store. Yeah, there are better deals available, but I'm still a fan. I may or may not have picked up another intro pack last night (which makes for my third intro pack purchase). Should you wanna pick up a ready-made deck, it's not a bad way to go. Still, I'd recommend hitting up MTG Salvation wiki to look at the detailed card lists of what lies within each deck. If you wanna be able to play in "standard format" tournaments, don't buy a deck that isn't of the Zendikar, Worldwake, or Rise of the Eldrazi expansions. Any other decks will not be in standard format for long.
(Trying to decide the best route for me and my friends)
