Killmonger is the best champ in this poll, however if you are looking for bleed damage only, then OML or Gwenpool are the ways to go. I prefer OML, but you really cant go wrong with anyone.
Him or OML. Both have insane damage with bleeds, although OML has better bleed damage. Killmonger can be used in Act 6 tho
I think if you specifically want a "bleed champ" Gwenpool is overwhelmingly the best choice. She has the best chance to apply bleeds and stack bleeds. If you need a bleed champ, odds are it is for some situation where you either need as much bleed damage as possible or for bleeds to be up as often as possible. I think Gwenpool is the best choice to cover both bases reasonably well.