Without question, true wild carp fight the hardest.
I get invited to fish a small well hidden farm pond every so often, and have done for many years. I would never miss an invite because it's so great there. Dark because of the dense tree line.
The carp in there, are slim lengthy common looking but, have a blue tint to them.
They fight incredibly, and pull like a barbel.

Commons, mirrors and leathers, I've never noticed a difference, some battle some don't
Always found shallow water fish seem to fight harder.

Definitely wildies if there is any still about, used to catch the on an estate lake years ago and you knew from the screaming take that you was attached to one

In reply to Post #1
I think a lot depends on gear being used and the water your fishing, deeper lakes they tend to plod more in the deeper water whereas shallow lakes they run more due to lack of depth or at least it feels that way.

For me of the carp over here ghosties fight the hardest pound for pound, but give me a 30lb + tope on a light uptider any day

In reply to Post #18
Or a 30lb toped on a carp rod in Aberdovey you know your hooked up

Ghost carp have always fought pretty hard, when I have hooked them.