Both are pretty good champs, you cant go wrong with either. I say go Emma because at your progression level she'll be usable in a wider array of content than iHulk ( mainly because of her long list immunities, gains prowess so can be used in Buffed Up node too). Mind you though, iHulk is also a hard counter to certain bosses and nodes such as Icarus and others, but they are more niche situations than the ones Emma can handle.
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She's got huge utility with her immunities, Taunt, and Unevadeable Specials. Go for it.