I've seen both. For me, Arabella was far better. They're both tall and slim girls, Arabella is very tall, I'm fairly short, and she was much more willing to take the lead which suits my personality she also provides a full on snog fest, OWO and CIM.
Would definitely see Arabella again, Amelia was okay but I wouldn't see again.
To save people asking why I haven't posted a review for these 2 occasions; there was a significant death in the familiy earlier in the year and I just haven't felt like it.