Affinity deck is crazy strong
and I also find packing your file with legendary creatures is also a pretty good strategy destroy everything
Which deck doesn't need to use lands? I find that the optimal amount of lands is around 16, but I guess it depends on how you distribute your low cost and high cost units. I'm starting to think well made rush files are strongest.
You haven't seen the original Mirrodin Affinity... The Magarena Affinity is the "new" affinity, which is much fairer, using Metalcraft instead of true affinity. The original affinity is the epitome of brokenness (i.e. you essentially play cards for free and draw cards like mad to refresh your hand)
For a 40-card deck, 16 lands is ok
For a 60-card deck, 22-25 lands are ok depending on what your goal is.
Also, Magic decks have no max deck size. There are 300 cards decks out there:http://www.mtgvault.com/ViewDeck.aspx?DeckID=13494
If you play Commander, you need 100 card decks with only 1 copies of each except basic lands:http://wiki.mtgsalvation.com/article/Commander
No land decks:
I can't find the article few years ago on MTG official site where there was an outlandish no-land deck. It was pretty cool.
Rush dies horribly to:Wrath of God
Legendaries are poweful? Sure! They are like characters in Alteil. Cards like the following does exist though:Mirror GalleryLeyline of SingularityHero's Demise
No one uses hero's demise because unlike Alteil, Legendary and big creatures are not that game-changing and are easy to deal with simple spells like:Go for the throat
or control:Sower of temptation
What cannot be dealt with is Legendary Flying Spaghetti Monster at its finest:Emrakul the Aeons torn
Annihilator 6 means that whenever that creature attacks (no need to deal damage, just declare attack), the opponent must immediately sacrifice 6 permanents (lands, enchant, creature, artifact, etc)
However, stuffs like:Final JudgmentOblivion Ring
Still work on it. However, if emrakul is out, it's usually gg.
Otherwise, big world snake works too:Progenitus
After all, it has protection from everything!
Take a look at the new cool dual-face transform card legendaries:Elbrus/Withengar