First matchup: Gold Iron Man. Though if I cared about DC figs, I'd probably save Blue Beetle, cause if I save Iron Man's mask I could just paint a regular Iron Man gold
Second matchup: Namor. Still have a shot at getting Moon Knight in stores, plus he'll probably end up being one of the variants you can $15 off of ebay eventually, if he isn't already.
Third matchup: Stealth Iron Man, unless the custom uses pieces from Absorbing Man, Dragon Man, Kang, Toad, and Dark Phoenix.