Hmm...there are and can be many different answers to this question. If you mean the most generic canines/felines on FH (wolf and lion) were fighting, then the lion would win hands down. But with the many different species and the infinite amount of situations, the answers would be dfferent every time. If you put one or two wolves up against a big cat, say a lion or tiger, the cat would probably win. Put a wolf up against an ocelot and the wolf would likely be the winner. Fox against an ocelot and the ocelot might win, though this seems more like a fair fight. Take a pack of wolves and set them up against a lion, the wolves would likely win because of their numbers, but have a pride vs pack war then I figure the pride would win.
Big cats like lions and tigers are bulkier than most canids. Their teeth and claws are a lot bigger, and basically just their size in general. They're built for hunting alone, though lions would be an acception. Canids like wolves and maybe African Wild Dogs are smaller and more social than tigers and leopards. Their pack is their greatest strength. A wolf could easily take down prey in a group, but might struggle on their own.
So yeah. Depends on the situation.