Chemistry is subjective. Not that it really matters, because chemistry or not, any relationship with Oliver isn't very well written and every female character is better off without him. But if the show was better popularity wouldn't matter.
I'll never understand when people say this. I think Amell and Cassidy have amazing chemistry on-screen together, just look at the hallway scene or the "This city needs the Arrow," scene from the end of Season 2. The problem is that the writers don't give them enough to do together. It's true that Felicity and Oliver had chemistry back when it was a simply playful one-sided crush but now that they're actually together I think the chemistry between the two actors is nonexistent and godawful. They drag down the whole show with every scene. It's all subjective I suppose though.
