Man, Reptile is the reason why I have "Reptile" in my name and have had it that way for fifteen years -- and trust me, he'd been my favorite since way before that. (Well, also reptiles in general). He was just so cool - this mysterious hyper-skilled warrior, who was GREEN, and also reptilian -- I loved the idea that he was a shapeshifter, and always favored his MKII storyline.
And THE HYPEST FIGHT. IN THE MOVIE. REPTILE. Perfect and fitting for the first secret character ever.
It was UMK3 when he started to become a little dumb to me - quite literally, they made him dumb. Why would he be loyal to Shao Kahn? At all? It was better in MKII when he was secretly bitter about it, like anyone who is the last of their kind would be to the man who committed genocide upon your race. And also the idea that he was skilled. At least in UMK3 they gave him the respect of saying that he was possibly responsible for the deaths of millions. (Though it always annoyed me that his blood was green. Reptiles don't have green blood.)
MK4 . . . I feel like I shouldn't have to repeat myself, I talked enough about MK4 Reptile on this forum back when MK4 was still relevant, but . . . purple-pants ninja. I thought his design was enragingly stupid, and I never thought I'd actually feel anything but dislike towards it.
MKDA was finally the design I'd always wanted to see for Reptile, and plus he did Hung Gar which was the style of Kung Fu that I practiced. He was fun and MKDA was just really hype in general, but again, his konquest mode story was just . . . he was so stupid that he was delusional. At least they had a very good explanation for it which was that he was devolving over time. I could deal with that. Plus, they came up with the idea of the matriarch (more on that with Khameleon).
I didn't like his MKSM design. Disliked it more than MK4. But whatever. By this time Reptile had kind of dropped off my radar, which is a shame since he WAS my absolute favorite, but basically he became a dumb enforcer.
But man, when MK2011 came out, and just completely took everything from him -- not only was he not special in the MK1 part of the story mode, but he was the first opponent that you fought and the first one to lose. Plus, his design, and he's completely irrelevant. An even DUMBER, and now INCOMPETENT, enforcer.
In MKX he's no more relevant than he was before. Like . . . he was this super-secret super-skilled hype super-ninja dinosaur assassin, personal guard of Shang Tsung, the last of his kind . . . and now he's just a toad.
I think Khameleon, despite having dubious MKT origins, could fit into that Matriarch part really well. Like a lot of characters, she surprisingly has a lot of potential if we forget that she was just a combination of all the female palette-swapped ninjas -- and we as a fanbase are good at forgetting about dubious origins. That being said, her potential doesn't stand on its own, though, because what's a matriarch without followers? I think that based on Reptile's MKX tower ending, she would BE that matriarch. I mean sure, she could replace Reptile I guess, but they'd be more interesting if they actually interacted at one point.
But I feel like that's a storyline that will never be explored fully and only hinted at in (Reptile's) tower endings.
tl;dr: Reptile was my favorite MK character for a long long time; Khameleon has potential but only in the context of Reptile or some highly unlikely Zaterra-related subplot; want both, but would choose Reptile on the off-chance they make him cool again (which would work better with her involved, maybe, and I guess Khameleon could stand on her own but why)
We've got chicken tonight. Strangest damn things. They're man made. 
