Became uncollected a week ago. Pulled 6* Red guardian 4 days back.
Following is the list of all 5* and 6* champs I have, and I am confused with which champ to upgrade.

Currently I use
4* doom and NF and Spidey Stealth/Corvus/AA 5* Massacre(80% i use him) or Namor or IMIW, 6* Red Guardian
I am learning to maintain my combo with aegon. Like almost everytime I loose my combo when enemy is about 15-20% just to finish fight earlier.
Also, I am just 1 skill t4cc away. So all options are open.