I disagree with the kages part xD Dan said only Hashirama could defeat Madara, we know neárly nothing of Tobirama & Hiruzens real strength and naruto has never met his old man before (only when he fought pain)
Those are somewhat interesting edos - but at the same time, I find them relatively 'cheap.'
You have characters like Mito - or any random Uzumaki from Uzushiogakure proper - who would have made very interesting edos. What better than a clan with techniques that were both legendary and almost completely unknown amongst those alive to be in the Alliance?
There are ways to tell a story and to fill in the history about legendary characters without evoking their character, directly.
Of course, I believe Edo Tensei has been made far too cheap. Unlimited chakra? Nearly perfect control over someone regardless of their knowledge and abilities? There are numerous ways to use Edo Tensei more tactically in a plot that would make using it on Kage and other high level ninja quite risky and quite a feat. There were other ways to give the Akatsuki an "army" than a bunch of Zetsu fodder and bringing back history's legends by the dozen. It's still not exactly clear where the "80,000" Ninja came from. Theoretically, the Leaf provided over 16,000 of those - and we saw the class sizes they had. The math doesn't add up.
Kishi could have written a plot with a fraction of the forces using strategic maneuvering of smaller details (rather than classic 'armies') and kept the 'ninja feel' to it all. This would allow techniques like Edo Tensei to be limited while still being exceptionally potent and useful (but with flaws that could be exploited in a few different ways). And it would mean that you could build more depth to the universe (and even some of the historic characters) by portraying them indirectly as opposed to directly.
But I'm kind of rambling and talking in circles.
The point is that Edo Tensei is just a cheap move to begin with. Revive history's gods and give them unlimited chakra. There's no reason to ever avoid using edo tensei on the most powerful people you can find.
I mean... what's this battle going to turn into? Hashirama with unlimited chakra versus Madara with unlimited chakra with Minato, Sarutobi, and Tobirama running as support with a Juubi complicating the mix. Oh, and none of them can really be destroyed (spare for, theoretically, the Juubi).
It's going to boil down to shooting a Kamehameha wave at each other for five chapters before it ends with a Father-Son Rasengan.
In the mean time - what the hell are characters like Tenten supposed to do?
Sure - Naruto and the Kage are supposed to be these powerhouse characters... but things have gotten so far out of hand that the only people who can do anything are the Mary Sues of the plot.
It's like different versions of Majin Buu fighting each other.
.
