There are definite differences in "magician" play diversity between 2e and 3e. Now, perhaps those differences pale in comparison to, say, between D&D and WoD, M&M, or Exalted "magicians", but I haven't made it that far yet.
But MtG? It's a great example of "very few cards are playable at optimal tournament levels", yet most cards see play at a casual level. Heck, because I play for fun (with still more than my fair share of wins), I've brought things like Cosmic Larva to a tournament.
At the level of "playing for fun" where most MtG cards are playable, most RPG options are also playable… maybe. Warhammer psykers will make the walls bleed before summoning demons that eat the whole party, and some systems will have casters sitting there for round after round doing nothing, not really playing the game. But, otherwise, there's probably few systems where you'll decide you need to throw out the bulk of the options as "unplayable". One level of every class (or, in this case, every "magical" class)? Yeah, a Wizard 1 / Sorcerer 1 / Cleric 1 / Healer 1 / Warlock 1 / True Namer 1 / Binder 1 / Incarnate 1 / Beguiler 1 / War Mage 1 / … probably isn't terribly playable. But I suspect most RPGs start with most content playable at low op. It's more a question of *how quickly* that narrows as you move towards high-op, I suspect.
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WoD vs D&D, I may be biased because of the GM's I've had.
Build diversity
WoD has 9 (or 15ish) playable groups ("traditions" and "conventions"), with different outlooks on magic, different techniques alter reality (from prayer to martial arts to hypertech). Although these serve as your class equivalent, it's entirely fluff, as they all have access to the same 9 spheres of magic, and can use those spheres to perform the same effects… if they can justify them. The new WoD has 10 spheres for 5 groups. Dark Ages offers much greater variety, with an unlimited number of spheres called "pillars" - if you can convince someone to teach you, as each group only has 4 spheres associated with it.
On paper, it would sound like a "Forces Life" mage build would seem very different from a "Spirit Time Matter" mage build. But, IME, since it's a "what they have now" rather than their potential (which are all identical), it doesn't feel as diverse as the difference between a War Mage and a Beguiler.
In play
A Forces Prime mage can create a Fireball. You'd think that would make him play differently than other mages. However, one of the principles of Mage is that there's more than one way to skin a cat. So a matter Mage could turn the air to hydrogen & oxygen, and pull a Roy Mustang. An Entropy mage could "oops, gas leak" out a Fireball. And, since they all want a Coincidence to make muggles believe there's nothing to see here, in play, whether it's kung fu fighters, hedonists, clone cyborgs, or new age crystal wavers, it's gas leaks all around.
And, because it's risky, magic is usually considered a last resort.
So, despite so much potential, Mage plays very samey.