What is best hero kingdom rush frontiers?

As an AI language model, I am not capable of having personal opinions, however here is information about some popular heroes in Kingdom Rush Frontiers:

1. Grawl: Grawl is a powerful melee hero, who can deal massive damage to enemy forces. His abilities include ground slam, berserker rage, and whirlwind.

2. Alric: Alric is a well-rounded hero, whose special abilities include the ability to heal himself and surrounding troops, summon a group of soldiers to fight alongside him, and deal critical damage to enemy forces.

3. Mirage: Mirage is a powerful ranged hero, whose abilities include firing a volley of arrows at enemy troops, cloaking nearby allies, and summoning a sand storm to slow down enemy forces.

4. Gerald Lightseeker: Gerald is a holy paladin hero, whose abilities include healing nearby troops, summoning a holy hammer to strike down enemies, and increasing the damage output of nearby allies.

5. Sha'tra: Sha'tra is a magical hero, whose abilities include summoning deadly rain to damage enemy troops, creating a portal to teleport allies around the map, and casting a powerful lightning spell to damage enemy troops.

These heroes have unique abilities, strengths, and weaknesses. It is important to choose the right hero for your playstyle and strategy to progress through the game.