Yeah, you can actually have two favorites like me, im an avid boxin fan and also have watched tons of boxin movies but definitely I have my favorite and that is
The Harder They Fall
It's the best depiction of the rotten side of boxing. The film portrays a boxing journalist (Humprey Bogart), who is procured by a shonky manager (Rod Steiger), to promote a bum. It's a smart, perceptive and accurate portrayal of the sharpness of professional boxing, and is punctuated by great performances.
If you want to see great acting, watch it! It's great from start to finish!
Rocky And Raging Bull Are Ties For 2nd!