How effective is fluoxetine in comparison to sertraline & escitalopram?

For what condition? It's important to know what condition is being treated -- so a good evaluation always comes first. Then helpful medicines can be selected if they're needed. Fluoxetine, sertraline, and escitalopram are all excellent ssri antidepressants with good anti-anxiety effects -- but there are some differences. An individual person may respond to one but not the others. Your psychiatrist can help select.