Pick Wukong when one Warframe needs to handle the widest spread of Warframe: The Old Peace missions with the least friction. Pick Atlas when you specifically want a grounded, melee-first brawler for dense combat maps. Pick Ivara when Spy vaults, laser grids, and clean objective runs are the reason for the investment.
The choice becomes clear the moment a squad splits at a Spy vault: Atlas can survive the firefight outside, Wukong can keep a normal mission moving, and Ivara can turn the vault itself into a controlled route. These three frames have real strengths, but they solve very different problems. Spending resources on the wrong one usually comes from judging their looks, durability, or novelty instead of the missions on your immediate path.