I have got them both fully covered. Cap’n is at level 280 and Spidey @ 300. Who would you spend your ISO on to champ first? Oh and the only 5* I have champed is Jessica and she is a beast. 
None.
Wait for a really good second 5 and enjoy the best MMR with your single 5* champ.
While Spidey is fun to play, I wouldn’t want to enter double 5* MMR with him and JJ.
And Cap definitely is not a candidate for your second champ.
The only other fully 5* I have is Archangel, which I guess is even worse. You’re right about them both. Thor is at 4/4/4, I’ll make him the only BH and hope for that. Thanks for input!
Oh yes, Thor is the one you want, definitely.
Set Valkyrie as BH to get that last cover.
Will do, thanks!
I have both Spidey and JJ champed and they’re a lot of fun together, I use Spidey’s red over JJ’s. Spidey can use red and blue and JJ makes nice trap tiles on both. Vulture makes a great third in the SIM keeping Spidey full of AP, though I use Chavez too - hoarding AP so she does her critical thing until Spidey has enough to whallop everybody left.
You also have a champed Okoye to fall back on.
OP is in a different place than you.
My 3/1/3 Okoye have a long way to go, I’m afraid.