Well, if we're talking about the X-Men cartoon which had founding members of Rogue, Gambit, Storm, Morph, etc, well...
It's an interesting comparison, as I had just the other day managed to put my finger on one of the weakness of the Justice League cartoon that I had not previously been able to articulate... and this is a weakness shared by the X-Men cartoon as well.
One thing that makes the Justice League comic book work is that the readers know the characters; the heroes don't have to develop during the League stories as they have their own comics for that. The idea of the League is to take these characters with their own involved and complicated histories (which we the readers know backwards and forwards) and bring them together.
The Justice League cartoon can't do this, of course. Apart from Superman and Batman, the cartoony League doesn't have any heroes like this. So, when we see the cartoony heroes gather, it lacks the synergy possessed by the real version of the League.
Oops, I'm rambling; that's not the flaw I mentioned above, though it's related to it.
Why call this cartoon "Justice League"? Because it's based on the comics? Ha! It's not based on the comics at all.
"But..." you might say, "but... the characters are the same, right?"
Well, no, of course the characters aren't the same. For example, John Stewart was almost never a member of the real League, nor was his personality like the one in the cartoon. Similar differences exist for the others, etc, etc. (Superman is actually one of the most powerful members in the comics.)
Okay, so the characters aren't the same. But the stories are, right? Well, no, of course not. You can't tell the same stories if the characters are different. Where's the story where Green Arrow joins the League after splitting a giant diamond in which the League is trapped? Well, Green Arrow will never join the League, so we can't tell that one. What about the story where Hawkman joins? Well, no, we can't tell that one. How about the pivotal stories where Red Tornado joins and dies and comes back and so on? Uh, nope. Meeting the JSA? Not gonna happen. Hawkman and Green Arrow's squabbles? Uh, nope. Etc ad infinitum.
So... why call this cartoon the League? The stories aren't the same as the real League. The characters aren't the same as the real League. Nothing is the same... except some slight similarity among names of characters and powers, etc.
In other words, the creators of the cartoony League have decided to adapt the Justice League into a cartoon... by changing everything about it. And that imho is not the way to do any sort of adaptation, whether it's comics into cartoons, comics into movies, or novels into movies. If you want to tell a different story, then you should tell a different story, with different characters, imho, instead of trying to pretend that there is any similarity whatsoever between the two versions.
And the X-Men cartoon was the same way.
(I bet you thought I'd never bring this back to the topic at hand.)
Any X-Men cartoon that has Rogue and Gambit as founding members who seek out new mutants like the Angel and Havok is just fundamentally flawed, imho.
Oh, and the animation was terrible, and so were the voice actors.
And the scripting was hardly stellar either. I used to try to count how many times we'd hear the sentence "Put me down!" since real violence was absent.
The X-Men cartoon was painful to watch. The Justice League is merely disappointing, so I'd have to give the edge to the Justice League.