Spider-man vs the Mandarin:
Okay, Peter's chances against Killian hinge entirely on the Iron Spider suit. Without that, this is a non-fight that Killian wins easily. With it. . . honestly, I think you all are under rating Killian. He's a dude who proved able to both tank and dodge attacks from Iron Man, and pretty much every time he touched a Stark-tech suit he destroyed it. The only way he was actually taken down involved first self-destructing an Iron Man armor with him inside it, and *then* shoving a missile inside him to detonate internally. Peter has much better mobility, sure, but I am iffy about how much damage he would actually do. Yes, the "instant kill mode", but based on the actual evidence in the movie I'm leery of assuming it hits as hard as a full powered repulser or IM fist, not when the only thing it did was "munch mooks".
I'd say Killian takes this 8/10. I give Peter one for "plays rope a dope until Killian tires out or overheats", and one for "Peter comes up with a smart usage of his available resources that I didn't think of". I'm not willing to go above that until and unless we get *much* better info on exactly what the Iron Spider armor can do, because I am not going to automatically assume "Iron Man Armor Stats" without evidence and where we know for sure the suit is built with different functionality in mind from Tony's ( or Rhodey's, or Pepper's ).
( And for the record, yes, I'd give Killian similar odds against anyone else in Spider-man's weight class. Cap wouldn't want to try to solo Killian, either. )