Right I'm not saying she's immediately top five but damn if she gets full control of the Phoenix Avatar (which she was born as a part of essentially), she's going to be unstoppable. She's been known as The White Phoenix so you could say she's been on par with Jean Grey's run as The Phoenix. Looking it over she's essentially immortal also since the Phoenix Force will just resurrect her with any injuries completely healed. She's not top 5 yet, but she has a built in advantage where she has the Phoenix Force on her side no matter what. With that she could easily surpass Jean Grey as being an actual part of the Phoenix Force should give her a massive advantage if she were to become the complete avatar of the Phoenix Force like Jean Grey did. The Phoenix Force tore Jean mentally and emotionally, Hope appears to be capable of being in full control where Jean only briefly had full control of it's power.