Neither. You need lots of buffs and lots of debuffs and neither of them can accomplish both of those things. Sure, Red Skull has his SP2, but then you're talking 50 SP2s. Sentry is far and away the best option for the path. Ironheart is another good choice. Spider-Woman, OGIM, Omega Sentinel...might be another one or two I'm missing, but that's a sufficient list to work from.
I believe I used Howard the Duck in my run. But it was quite some time ago
OP, the folks on the forums who are best able help you probably completed the content a long time ago. You’ll get better results if you write out the nodes and eligible champs (including which champs from the pool you actually have).
You need at least 3 buffs to make damage and a champ who places several debuffs (parry stunt debuff doesn't count for this node), Ironheart or ultron works great, sentry too, with red skull will be a very long figth, since he only place debuffs with Sp2,
You only need the 3 buffs for the Adam fight.
Each fight is different in that way, but you must place debuffs to do any damage for all fights.
Sentry and Photon did super well for me in this path. Shuri might be a good addition as well for the northstar fight. If you don't have sentry then you will need someone else with buffs and debuffs. Spider woman would do good on most fights and should be able to handle that one as well. Ironheart could also do that one. Howard the duck is a decent option for the adam fight also. Omega sentinel can work here too.
For all the other fights other than adam and who haven't been mentioned, these will all work pretty good as well: Nefaria, Deathless shehulk, silk, quicksilver, joe fixit (on those that bleed), arcade, titania, anti-venom, high evo, leader, luke cage, lady deathstrike, spider ham.
Read each node though as they are all unique and you don't want to be roadblocked. I think that Adam is the only one though that you need something else other than just debuffs.