The biggest!
This is Kelly Toy's BIGGEST (known) Shadow plush, at a whopping 70 inches! (That's 5 foot 8 inches) He's super big...and actually pretty cool. The giant size means the shoe & glove details really work. They also couldn't skimp on the hands/fingers size/proportion and detail, either. The head shape is even good, as are the spikes. The ears are simple flat triangles that flop down (too bad) but the eys, expression & lower face are good.
Kelly Toy isn't known for their powerful quality, but really this guy's not bad at all! He's not 'all leg' or noodly, either, like some other sizes. Shadow is filled with those styrofoam pellets at this size, to save on materials & weight cost. At right, you can see him compared with their 50 inch & 30 inch sizes, which are regular polyfill stuffed. If you have the space...this is a fun plush to own!

Opinion zone: I consider this "Life Size", and thereby, feel it is cooler than other dolls. I never really thought Sonic characters looked 'right' when they were these dinky, 3 foot high "tiny animals" type portrayals. Having them as tall as a regular human always looked/felt more "realistic"* to me,..so these giant dolls are automatically cooler.
The temptation to modify it would be there as well, like fixing the hands into having individual fingers, stuffing it with polyfill in the body or maybe adding 'funnoodle' strips to make it pose-able so it becomes more like a soft action figure to pose for fun photos or just to be able to stand out of the way since it takes up a lot of space by its very nature. Keeping a giant plush out of harms' way (harm being sunlight, moisture of the air, dust, pets, toppling off of stuff, powdery mildew, or any of the problems that can beset fabric) is also a consideration in collecting. However, something like this is a great collection centerpiece & a rare prize to own!

*I have no idea why. They are very abstract characters no-matter how you slice it.