Higher, Further, Faster

In the core set, Captain Marvel is arguably the most reliable hero, which fits her role in the comics. The other heroes have weak points (Spider-Man is not great at thwarting), weak cards (She-Hulk), or trouble with consistency due to reliance on drawing the specific cards (Iron Man and Black Panther). Captain Marvel really doesn't have any weaknesses. Her stats make her reasonably effective at thwarting and attacking, she has good card draw, the best resource card in the game (Energy Absorption), and good damage output. And the justice aspect in the core set gives plenty of good energy cards to power her effects.

Piloting notes:

Hero/Alter Ego management. Since you can switch back and forth at any point in your turn, the main difference it makes is what happens in the villain phase (attack or scheme). This deck has good thwarting capability, allowing switching almost every turn to maximize card draw and reduces the need to recover often beyond Captain Marvel's healing effect. You should generally try to activate both Carol Danvers' and Captain Marvel's built-in powers every turn.

Captain Marvel's Helmet, Cosmic Flight and Crisis Interdiction: mainly good when you have them together or when you need the defense from the first 2. Otherwise, use them for resources.

Energy Channel: play it right away and charge it every turn.

Heroic Intuition and Interrogation Room: extra copies go to Energy Channel and the other energy resource-requiring effects. Likewise for Jessica Jones unless there at least 1-2 side schemes in play.

Avengers Mansion: play if you get it early, otherwise use for resources.

Emergency and Haymaker: usually used for resources unless circumstances (side schemes or minions) require use.

Photonic Blast: use as soon as drawn.

The Power of Justice: A little better with Captain Marvel because it can also be used as an energy resource.