Originally Posted by
Plawsky
It's tough to compare, because it's so unique. Almost every other alternate universe was either short lived or not a direct parallel universe.
The short lived versions - 1602, Earth X, etc - are obviously less developed, having usually only a handful of issues, sometimes up to a few dozen, and typically all in one title or consecutive miniseries. That's compared to the hundreds of Ultimate books across several titles and loads of minis.
The others aren't really the same kind of "parallel" that the UU is. Some examples: Marvel 2099, Earth-2, New Universe, MC2. These feature either completely different characters (New Universe) or alternate futures (2099, MC2). Or, in Earth-2's case, it has the parallel characters, but it typically focuses on different ones, emphasizing the JSA over the parallels of Batman, Superman, and the JLA characters.
The most similar project is probably Earth One, because it's doing exactly what the Ultimate Universe did 14 years ago - create a new, connected universe featuring updated versions of classic characters. But currently, it's still way behind in quantity, though it's expanding quickly soon.
Historically, MC2 and 2099 are probably the closest things as far as long-term goes. Neither one lasted as long, but they feature different versions of Spider-man, the X-Men, etc. However, the versions there are mostly children, descendants, or just new people taking up the mantle, rather than following new stories of Peter Parker, Charles Xavier, and Reed Richards.
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Quality-wise? I'd always put the UU at the top, in no small part due to its scope. But I'm a sucker for alt-universes. I love 1602 and have a custom bound hardcover with all four of its miniseries and the Hulk 1602 short story. I think 2099 is fascinating. Earth X didn't blow me away, but it's a fantastic idea with some amazing designs.
The very idea of alternate universes is always cool to me, and history has shown that, at least in the short run, it almost always ends up working pretty well.