565
Miniaturule
(i.imgur.com)
Be sure to follow the rule before you head out.
Rule: You must post before you leave.
There are periods in the game's history where various formats were well designed and balanced and thus had a wide degree of viable decks, making the game generally enjoyable to actually play at both a casual and serious level.
Unfortunately practically nobody can agree on when those times actually are.
Draft and seald formats have also been consistenly popular and they completely exclude the collection aspect.