Here are some names I think would be be great (and coming from someone who would also not use a name b/c of the Ellie nickname):
Hollis
Blair
Rainer
Dillon
Ever
Piper
Romy
Fable
Jude
Remy
Harlow
Emery
Sloane
Vesper
Fifer
Micah
Kit
Sunday (can nn Daisy)
Bellamy
Morgan
Robin (not sure if it & Morgan to similar in pattern to Arden)
Holland
Shiloh
Holiday
Hope that helps!