The Hexagonal Donut
Plantera
Or it can be nixed entirely, because something just occurred to me.
There is literally nothing about Jade that correlates with Crimson beyond color. It's themed after nature- something that actually is closer to what Crimson is than it is an opposite by a massive margin. Literally the only thing that correlated with Crimson is the color- green, which is a complimentary color for red, which is obviously Crimson's color. The only thing that would make Jade an "opposite" to Crimson is that and it being a "light-ish" evil.
To contrast, let's look at Cyber, probably the best and most popular candidate for a Hallow alternate and Crimson opposition. First off- metal versus flesh. That alone speaks volumes: In a lot of cases, metal tends to oppose flesh in some way, usually in a sort of "robots versus humans" kind of aspect. This already speaks volumes in Cyber's favor, but I'm not done yet. Where Crimson is flooded with all sorts of random enemies and creatures (which presents a degree of chaos when you also consider the chaotic and unpredictable structure of its tunnels), Cyber's enemies are fairly uniform, sleek, and clean- order. Two things that also oppose each other. As well, Jade is just a generic infection, but Cyber and Crimson don't convert- they consume (because let's be honest, it's pretty hard to convert stone into steel or flesh). Another point of correlation. Sure, their grass colors aren't complimentary, but neither are Corruption's and Hallow's. (For the record, a complimentary color to purple would be closer to yellow than cyan.)
(tl;dr: there are a lot of points of correlation between Crimson and Cyber and only one or two between Crimson and Jade)
I'm going to be completely honest. If you really don't like Cyber so much, then actually think about the things that make it such a good opposing force to Crimson and try to make something better (in your eyes) with that information. Just opposing colors isn't good enough.
There is literally nothing about Jade that correlates with Crimson beyond color. It's themed after nature- something that actually is closer to what Crimson is than it is an opposite by a massive margin. Literally the only thing that correlated with Crimson is the color- green, which is a complimentary color for red, which is obviously Crimson's color. The only thing that would make Jade an "opposite" to Crimson is that and it being a "light-ish" evil.
To contrast, let's look at Cyber, probably the best and most popular candidate for a Hallow alternate and Crimson opposition. First off- metal versus flesh. That alone speaks volumes: In a lot of cases, metal tends to oppose flesh in some way, usually in a sort of "robots versus humans" kind of aspect. This already speaks volumes in Cyber's favor, but I'm not done yet. Where Crimson is flooded with all sorts of random enemies and creatures (which presents a degree of chaos when you also consider the chaotic and unpredictable structure of its tunnels), Cyber's enemies are fairly uniform, sleek, and clean- order. Two things that also oppose each other. As well, Jade is just a generic infection, but Cyber and Crimson don't convert- they consume (because let's be honest, it's pretty hard to convert stone into steel or flesh). Another point of correlation. Sure, their grass colors aren't complimentary, but neither are Corruption's and Hallow's. (For the record, a complimentary color to purple would be closer to yellow than cyan.)
(tl;dr: there are a lot of points of correlation between Crimson and Cyber and only one or two between Crimson and Jade)
I'm going to be completely honest. If you really don't like Cyber so much, then actually think about the things that make it such a good opposing force to Crimson and try to make something better (in your eyes) with that information. Just opposing colors isn't good enough.